How does the process work as far as paying for the silencer/weapons? Do I need to open an account for the trust to buy weapons with, or can I just pay for them myself?

If you already have a Trust, then you just put the Toy & Tax Stamp in your Shopping Cart.
Pay with your CC.

It is as quick as shopping on Amazon etc.

They will send you an email with an Order# & Serial#.

Email, Fax etc a copy of your Trust.
DONE.

what forms do I need to fill out, or do they take care of that?

I believe ordering online is similar to buying directly at their store in Austin. Difference is they must either email or mail you the documents for necessary signatures.

1. Purchase the Can
2. Trust $129.95 They print it, you sign it, they notarize it,and they submit it electronically. Future Can's purchased are added to the trust but I didn't ask what that fee is.
3. Tax Stamp $200 + $5 for them to handle sending it. They print the paperwork for your signature. The tax stamp is per Can.

Once you select your Can (s), it takes maybe 5 minutes to complete the documents.

BTW you must know the thread diameter of the barrel you will add the can on. The common sizes are 9/16, 5/8, and 1/2 ( I'm not on a computer to verify this) but its important to determine the thread size of the can and whether there are thread adapters for the barrel and can threads. For me, it made a difference on the 6.5 Grendell upper i wanted to order. You would think there is standard but the two most popular sellers have
different thread sizes.