Fabia 05 vrs help

Been to look at a lovely VRS yesterday and few little things I was hoping someone could advise me on.

1st the oil level was a live the top fold on the dipstick, it was cold and a tiny lean to the curb but nothing major. Also there was a pool around the filler cap like someone had spilled it. Is this a problem? I would have to drive hour and half home so this would be ok?

2nd noticed a line of what looked like water marks on the rear seat, drivers side. Looked like door wasn't shut or window open but I've read seals can be bad so how hard is it to change seals and does anyone know how much they cost? Seal looked good so was hoping just door or window open as marks are faint.

It's got amazing history and really good condition bar the last service (100 miles ago) that was done at a local garage.

Any advice please peeps?

Cheers