(Old Memory Warning) Since you are cleaning up the electrical connections... Take a look at the plug that connects the wire loom (on the right side under the dash). I had this fail (melted) after I increased the load by adding H4s.

Regarding HID (summarized from what I've read)... these draw less voltage than H4s. You can get kits that adapt them to H4 reflectors. Legal here? I don't know. Typically HID are low beam only. The high beam on these is Halogen due to the HID taking a few moments to warm up. You won't have full power when you flick the high beam on if it's HID. Opinion here... Is it worth it? The question is how much are you going to be driving at night?

I'm running into this same problem ATM.. Is there any easy upgrade of fuse box out of a different car maybe?

Not even new cars uses a heavier duty fuse box for HIDs. They use a headlight relay. You can do this too for the 1200, see Headlight Wiring.