i personally wouldnt fancy a fiesta, they're just a bit too small. THe focus is lovely (i had a mk1 focus when they first came out) so I may be a little biased. They ride very well, they're nippy enough on any motorway. I think the 1.8 has 115hp as standard, not as torquey obviously as the tdci but adequate for a daily runner.
Bits are cheap from eurocar parts, breakers yards are FULL of focuses so you're never left looking for a part. I pulled the front brake system off a focus st170 in a breakers yard and bolted it on to mine, the discs are massive and the calipers are huge. I'd do the upgrade on ANY focus i buy in the future, you simply CANNOT have too much braking power! especially around town when every f**kwit in front of you wants to park in a tiny space theyve seen at the last minute!