A Few 454 Questions

Hi there folks! I've recently built up my own version of the ZZ454 crate engine that GMPP offers. I purchased the 454 short block from GMPP #12498778, and to it, I've added Edelbrock Performer RPM oval port heads #60459, an Edelbrock Performer RPM Air Gap 2-0 intake manifold #7561, and a Comp Cams Xtreme Energy hydraulic roller cam #XR276HR. I'm running it with the same pushrods and stamped steel rocker arms as would have come in the complete ZZ454 crate engine, as well as an Edelbrock 750 CFM Performer Series carburetor #1407, and a full MSD ignition system, including a pro billet mechanical advance only distributor #85551, and the classic 6AL box. I'm running this in my 1981 Caprice, with a TCI Streetfighter TH350 transmission, a TCI Breakaway torque convertor, and the 7.5" rear end, but with 3.73:1 gears. As for my questions, I was wondering about the following:

1) I properly primed the oiling system on this engine for several minutes, this is something I've never bothered doing on any previous engines. After completing the job, I noticed a rather large pool of oil under the engine. I checked all the obvious areas, and I've concluded that it appears to be coming from either inside the bellhousing, from the back of the block, as the flexplate has some oil on it, or possibly (and I'm hoping) it came from the distributor hole while priming. Does anyone know if this complete short block has open oil gallery holes in the back of the block? Or would it appear that this was just oil that was pumped up and out the distributor hole from under the collar of the priming tool?

2) Another question regarding the oiling system of this engine. The oil filter area has the threaded nipple to use screw on filters, however, it's not the large bronzish looking thing that I pulled off the original 305 small block that the car came with. It's just a plain nipple that screws in the block, and has a female hex end to it. There doesn't appear to be any leaks in the oil filter area, however, did I do this right by just threading the oil filter onto this nipple, or should I have unscrewed this, and installed the adapter sold by GMPP under the #

3) Based upon the specifications that I provided at the start of my post, what type of base/total ignition timing figures should I be looking to adjust it to? And, what type of springs should I be using in the advance mechanism of the distributor?

4) One final question here. With that carburetor, would I typically be fine with just leaving it jetted the way that it came from Edelbrock, or would it be best if I was to acquire a jet and spring kit and have it dyno calibrated?