Hi, Paul and welcome!
1) It's dead easy to change the interior light. Gently prise off the lens (between the sun visors) and remove the bulb ('festoon' type - available everywhere)
2) Could be power steering on the way out... Check the fliud reservoir and top up if necessary. Operate the the steeering lock-to-lock a couple of times and recheck the fluid level.
3) Could be a blown fuse. Fuse box is under the bonnet up close the to windscreen on the LHS
4) Unless your GF's a speed freak (in which case why buy a cabriolet...?

), probably not..., but it's your/her money...
5) It's much easier and cheaper to change the bulbs for 'high brightness' ones.
6) The dash lighting is pretty pathetic. You can use 5 W wedge bulbs in place of the 3 W originals, but they do get
very hot and can melt the fitting. LED bulbs don't seem to be much better, but you could try the 'stacked' 5Ă—SEM (at least)... Also the silvering on the light guides in the dash module can crack, flake off, discolour, in which case no bulbs will help...