question about locks.

[snakesRkewl]

Chances are they didn't and unless you witness a lock it doesn't count for anything more than an attempt

If I leave them together for the three days will they lock again (assuming they have already locked)?

Only they can tell you that

should I be feeding them regularly while they are pairing. (On their break days)

Absolutely, feed them during breaks.
3 days in with her is a guideline, not an absolute.
You want to use small males sparingly because when a 500 gram snake goes off feed you have a limited time to use him before he gets too skinny to continue.

My Spider female is on ASF and she eats regularly every 2 days (although she's refused lately). Will breeding them entice a feeding response?

Sometimes, not much help but it's the truth, sometimes breeding them makes them ravenous and other times they shut down completely.