[Marianitem]

Welcome to the forum!

Before my tips for you let me ask something about the Pearl Clear you were recomended: does anybody know if there is any PEARL CLEAR paint sold not as spray? I cannot find TS paints in my country, and shipping them is a bit problematic. Any suggestions?

Now, some answers to your questions

About your Q on thinners:
Regular option is X20A. You can buy it in big bottles. But, as it smelled like alcohol, I decided to try something cheaper.
I use almost exclusively Tamiya Acrylics for all parts related to interior, chassis and engine (everything but the body). For that purpose I thin them with alcohol (the one you have in your emergency box, medical use, you name it). It actually dries very fast when airbrushing so it saves you lots of time. There´s no compatibility issue, at least with every alcohol bottle i have used so far. I also use it to clean my AB and brushes, and to soften the brush while brush painting details.

About primer on interior and small parts:
It is recommended to use primer Always, as it helps paint to stick to surface (it works). Anyway, when I have a 1/24 chassis molded in black, and I will finally paint it black... I don´t want to waste so much paint, and I´m not a fan of detailing chassis. So I just give it a light shot of the same color over the bare plastic and that gives it a little bit of texture, a "painted look", good enough for me. But if you are a purist, apply 3 thin layers of primer, then sand down to desired texture, then use all the paint you need to cover everything to the desired color (definitely not my choice). I also use my economic technique on chassis parts that are already molded in the color I need them.
I found a primer on an art warehouse/store. It is sold as a thick cream or "paste" (like toothpaste you know). I also thin down with alcohol. It is really cheap, thinned cheap, applies perfectly smooth and it works.

Clear parts for lights: you can use "clear red" or "clear orange" acrylic paint for them. x27 and x26. A jar of each will last you for ever. Beware they are kinda tricky as they get sticky.

Tip: get some X22 gloss clear, but not only for the gloss effect. Acrylic paints, specially flat colors, may become a bit fragile and rub off when manipulating. If you are going to mask a paintjob, first apply primer, then paint first color, apply a thin coat of clear to protect it, then mask, then paint second color. Sounds like a PITA, but it will save you headaches.

Hope this helps

BTW: using the products I mentioned I managed to take every interior and chassis part from the R35 Fujimi kit, primer everything, paint everything on about 6 colours, brush paint details, and assemble full chassis in half a day. Please note that I work very slowly.