Provider based billing rules can indeed be challenging - I dealt with that for many years. Unfortunately, I don't know of good resources for this, although there are some companies out there that do provide consulting and/or seminars on the topic which could be helpful (but also tend to be expensive). Ideally, the billing system at the hospital responsible for your clinic would be set up to automatically split the professional and facility charges based on each payer's requirements and not require coders to have to do this manually. Your compliance department should also be involved with you on this to ensure you're meeting all of the legal requirements for this status, of which there are many, including giving appropriate notice to patients, and your status as on/off campus and excepted/non-excepted (i.e. if and when to use PN or PO modifiers).
In any case, to answer your question, for payers that recognize your provider based status, all technical charges for x-rays have to go on the UB claim and all professional charges go on the 1500 claim - you cannot bill globally if you are billing as provider based. On a UB claim there is normally no need for a TC modifier since it's understood that this claim type is only for facility charges. But on your professional claim you should include the 26 modifier since a 1500 claim has the capacity to bill for technical charges. Although most payers should know from your POS code 19 that this was done in a facility and will likely pay you correctly just for the professional component even without the modifier, in my experience it's best to include the modifier to prevent an overpayment error and/or have to deal with an audit or recoup problem down the road. Hope this helps some.