I think a tablet is to big to be totally honest. Do the double DIN swap if you don't have it and throw a good touchscreen unit in there with BT to link to your phone IMHO.
As for the bulbs, yes there are 5 LEDs in the cluster and 2 in the HVAC. WLED-5 on superbrightleds.com is the bulb you want.
There really isn't a super lot you can do really though. Cluster update with a newer one or a Florida
5.0 one, the Florida 5.0 clock pod replacer if you have a hole for one (or cut a hole if you don't), better seats, LED domelight/reading lights and if you are good you can solder LEDs into all the switches too.
I mean the newest one of these cars is now 10 years old and the design is from the early 90s at the height of the jelly bean era for a production run starting in 1993. I think we are lucky it has aged as well as it has and that there really aren't any issues with warping panels, cracking dashes or anything like that. The interior in my 98 is swapped with one out of a 95 V6 and with new carpet, new upholstery and some detailing it looks about as new as one of these interiors can.