That might indicate a very big advantage in this rook end game. But rook endings are notoriously hard to win.

Rc1, preparing b5... just too "naive"?

I find it hard to hit on any alternative plan here. The plan suggested by damalfi looks as good as anything: get the rook behind the 'candidate' passer.

I agree. Exchanging rooks would have been a terrible mistake. But maybe ...Rh5 ought to have been preferred. Maybe.

Another idea was 25...Rh5 26.h4 g5. That is why I rather prefer ...Rh5 the previous move with the same idea as the text, but different pawns coming into play. Another idea worth looking into was 25...a5, in the hope of breaking up or weakening White's Q-side pawns. It is one of those moves I'd look at and probably reject, unless things were getting desperate, or I could really get in amongst those pawns.

This probably rules ...a5 out of court.

Probably best. Who knows how this would have gone: 28.b5 hxg3 29.hxg3 Rxg3 30.c6 bxc6 31.bxc2 Rc3 32.Rd7ch Ke3 33.Rxg7 Rxc6 34.Rxa7 Ke5. Probably a draw.