I think you are asking if autococker barrels will fit on an A-5. The answer is no; Autocockers and A-5s use completely different threads.
99.9% of all guns made in the last 14 years have removeable barrels.....however they use many different "threads" on the barrels and you must match the new barrel to your old barrels "threads" Most common Threads are Autococker Tippman 98 Tippman A5 Spyder and Impulse The most common is Autococker (Dye, Proto, Evil, Infinity, Automag, and Eclipse use this thread)
Autococker threaded.
No, it uses autococker threading. There are currently no barrel extenders with the A5/X7 threads.
there are many avenues to find barrels for A5's. Try the "gunbroker.com" firearm barrel section. A5 barrels are sold there all the time.
No. They have specific brand to type of threading. The major threads are: 98, a5/x7, spyder, autococker and ion.
Yes
As more companies started making Paintball markers, there started to be MANY companies that made aftermarket barrels, however it was cheaper for them if there was a universal fitting for the barrels instead of dozens. Many of the companies decided that WGP's Autococker was a popular marker with a strong but easy to make barrel thread, and adopted it as the thread most barrels would be made in. To this day, even with WGP's decline, it is still the standard thread for most markers.
No.
No, spyders use spyder threaded barrels, where tippmans use either 98 or A5/x7 threads.
No. The Bt4 uses A5 threads, and the Tm 15 (a modified invert mini) uses Autococker threads.
Will probably require some gunsmith assistance
It depends on the threads of the Apex barrel. If the threads are that of a autococker, A5, or spyder then no, it will not fit. Though if it does have Tippmann threads then by all means it will fit.