Papez

Wow, that's actually more primitive than ones in Felicia, which had basic automation. They also had some "bonus" functions not wired in the factory installation - as motor units were re-used from VW T4 - like secondary switch or disable signal (so they can be adapted as rear windows). Unfortunately, the outside control wasn't amongst the functions - although, there are two pins with an unknown function.

Wow, it's serious downgrade then, because that function was present in MK1 and MK2. Does it at least have one-touch rollup/rolldown? Yes, Felicia's Windows do require some extra wiring, but for example mirror switch can use the same power input as windows. And windows are at least smart enough to have one touch rolling and do work for some time after ignition is switched off.

You don't need to turn the ignition on to move windows on the Fabia. All windows can be rolled up/down from the outside by holding the key in lock/unlock position. As long as the microswitch in the lock works 😀 As long as the motor's have automatic functions to roll up/down, it's definitely worth it.

Yes, it is a rebranded Inca, but Inca is derived from Ibiza Up to the B-pillar, they're nearly identical, just like Felicia/Pickup

It's a coolant drain plug.

You'd need to replace the rear beam. 93 favorit and Felicia had different mounting for the stub axles to fit MK3 golf brakes.

Caddy pickup or caddy van? The Pickup is just rebranded Felicia, so it'll fit, but the Van is based on Seat Ibiza, so the mechanism Is different.

Pretty much yes, 136 have flat pistons, while 135 have an oval recess. There was a huge variety in camshafts and heads, IIRC, the 136B had the largest duration, while the 136M (Felicia) had the best head design. The 136X also had a different ignition timing to achieve a bit higher power. Maybe I could find some more information. Yes, the head design is the same, as the 135 has been derived from the 136. I think that were attempts to chip tune the ECU, but it requires hardware mods. Maybe it'd be easier to get carburettor instead. Turbo was done on the MPI engines, but it's a lot of work, which requires custom software and ideally a Fabia block.

There should be a sticker in the engine bay. Felicia can have 3 variants of AC, only one is documented in the workshop manual - can you post a photo?

I don't think there'd be any gain, as the hole provide enough air for the larger 1.6 and 1.9 rads. Back to the topic, IIRC, the grill and chrome frame on the facelift model is identical to the Octavia MK1, so there might be some options. However, mounting around the chrome frame is different on Felicia.

Yep, it extends more in the bottom portion and helps direct air to the radiator

Early Favorits had just small slit, I'm not sure whether it did anything to cooling.. however, I've read numerous topics about Felicia front swap, where removal of the scoop behind the bumper cover lead to reduced cooling performance. Yep, and it's same on the other brands, like my SEAT with considerable smaller grill:

Felicia/Favorit was designed to supply cooling air through the bumper, the grill is mostly cosmetic - 1990-1992 Favorits had no grill at all. I've even seen some flow simulations that showed that grill can actually take some air away from the radiator, due to low pressure area on the bonnet edge ( probably reason why the newer Škodas have top portion of the grill blocked out)

256mm conversion is well documented. I think that some variants of Mondeo had the same calipers. But it doesn't work with 13 inch wheels. Some variants of Sierra (non-ABS I think), had 238mm discs and calipers with 54mm piston, which should be the same as Felicia. But I don't know which discs can be used with that conversion

If you want vented discs, you need to get suitable Ford calipers and fitting discs.

I cannot imagine 13mm thick vented discs. They are usually around 20mm thick. The picture is just some stock photo, I doubt it shows the actual disc.

Lauretas were based on Felicia. Favorits could've been custom mods or prototypes, they mention that Skoda tried longer variant of the pickup, but it didn't fit painting box on the assembly line. There's also one prototype built by Skoda factory, with longer wheelbase. https://skoda-virt.cz/cz/auta/favorit-a-felicie/10026-ota-jezevcik/

I'm not sure about that, most of prescribed plugs for the 136 engine are 0.7-0.8mm, but gap is not the only parameter that affects temperature rating, so it is hard to say which plugs are right without testing. That's why I'd keep plugs recommended by the manufacturer.

06A is code of the EA113 engine family, so I doubt they'll be the same.. I'd just get the NGK probe.

That's because DR15TC is a triple electrode plug. DR15YC, which has same parameters except for the electrode shape, is present in the list. DR15TC and RC89PYC are listed for Fabia OHV, too.

You should use Brisk DR15TC or similar with 0.8mm gap, which are recommended by the manufacturer. In the past, I tried NGK BKUR5ET-10 with 1mm gap (also recommended in the service manual) and those caused misfires after some time.

The original sensor was made by NGK. This confirms it. According to their catalogue, replacement for 6U0906265E is OZA457-I1

Stiffness doesn't equal durability, Chinese rubber is stiff as hell and doesn't last either 😀 but the original mounts atleast provide some noise insulation.

It depends on position of the differential cage when the driveshafts are removed. If you're not lucky, the gear might fall out through the hole into the gearbox. If you were able to put driveshafts back and they engage with the gears, it should be OK.

I think that Rubena (the original supplier) still makes rubber mounts locally in original quality (for roughly the same price as the Chinese parts), some brands might still use them. You can identify them by this logo