Before approaching lenders I suggest reading the VA Lenders Handbook. It is the big picture regarding VA loans. If you really go in depth with reading it you can learn how to manually calculate a loans chance of approval; what the underwriters are doing by software.
VA.gov | Veterans Affairs
The VA underwriting or lending requirements are very broad. So, when talking with a bank/credit union ask about their overlays. Example: VA lending requirements do not have a max debt to income ratio, but many lenders do. They may have an overlay of say, 54% or 48%. The DTI max is not a VA regulation, but the individual bank or CU's.
My experience with how they treat income has varied. Most banks and CU's will take VA compensation, and other non-taxable income, and gross up; add 20%. Ex: VA compensation is 2k a month. Because it is not taxable the gross and net income is the same, 2k a month. When they gross up by 20% your income is 2.4k a month.
Some lenders do and others do not gross up. That is a question you ask them when you talk about overlays, reserve requirements, etc. There is a Fannie and Freddie influence, but from what you are looking for I do not see a reason to go into that discussion. That is what the banks/CU's are paid to do and know, but you need to know if a bank or CU is right for you before investing your time and energy in one that may later decline to write the loan.
Yes, TDRL compensation can be used. Typically the banks want to see or anticipate 24 months of income. If placed on TDRL I would explain my VA compensation as "not changing anytime soon," and DoD as "not changing, but if going to change at the earliest, 18-24 months (re-eval in 18 months plus a few months for processing, appeals, etc.).
Personally I have worked with USAA, NFCU, Prime Lending, Mann Mortgage, and a few others. I have had great and terrible experiences with lenders, but that differs for everyone. Ask the right questions, speak at their level, and if you have any questions do not hesitate to ask. I am willing to toss in my two cents.
Finally, understand that just because you have a pre-approval or pre-qual from one lender does not mean that you need/should go with them, or that they will not later refuse to write the loan. I use USAA for my pre-quals because they are relatively easy and fast at approving and generating the documents I need to make an offer. Plus, sellers and sellers brokers tend to think highly of USAA pre-qual. Because of their (USAA) business model (terrible communication and out sourcing) I tend to close with other lenders.