3.) since my timing was 16BTDC, could i adjust the timing through the distributor even tho' its an OBDII motor? i thought my ECU automatically adjusts the timing as effecient as possible to prevent knocking?

You should be able to adjust base timing with the distributor. Your ECU only advances timing (makes spark occur faster) as your engine turns faster. Base timing affects where the spark actually occurs. The ECU only retards timing to prevent knocking whenever the knock sensor sends a signal to it.

4.) are there any products you stand by that would clean my injectors, knock away carbon deposits, etc? do you even think its necessary since i got my engine rebuilt not even 3500 miles ago?

I've heard good things about the Berryman 3-step fuel system maintenance kit. It cleans your fuel system, carbon deposits in your engine, and air intake system. They have it at Kragens for $20. If you had your engine rebuilt that recent then it's not necessary at all. If you want to burn a little leaner, widen your spark plug gap for hotter spark.

Good luck.