1. Headset - you'll need precision measurement to be absolutely certain you're getting the correct size. It's going to either be Italian, English, or ISO (and they are all close enough in size that measuring without a micrometer might get it wrong). Also, be sure to take the length of the steerer into account before deciding on one to get. Stack heights can vary considerably. Too tall, and it won't secure the fork. Too short, and you'll have extra steerer poking out the top.

2. You will be looking for a braze-on front derailleur. Not sure if they still make them, but they can be found without too much trouble. Many contemporary gruppos at the higher end of the model ranges offered two FD types - clamp-on and braze-on.

3. Not sure what you mean. The terminology is not familiar. Maybe if you can find some pictures to show us?