Looking good mate, just one thing I can;t make out.... Do you have the ab button plates and are yet to glue them on? Your ab plate should look like this
not without the plate (like a TD) as your looks from your photos. If you don't have the ab button plates, try sending one of the makers a PM, or ask one of your garrison's Sandys. They may have a spare set you can buy
Also, it might be worth considering toning down the paint scratching too. It's just a little too much for my personal taste, but it's up to you. Maybe try painting over a majority of the white marks, and by adding in scratches going in diferent dirrections, just makes it look more natural "battle damage" rather than having the same direction which looks like you've been dragged along the ground behind a landspeeder
As for your questions,
1. Not really sure what you mean here, sorry.
2. Jesse TK4702 makes awesome thermal det clips and kits. Just look for them in the For sale section.
3. Yep, humbrol #5 is the right colour for the thermal det tube.
Any more questions just ask