alright I know a decent amount of theroy, im not a master by any means, but im terrible with timing and time signatures. My question is how do I find out bpm im going? Also if my song is a basic 12 bar blues that goes E7, A7, and B7 I can just use the E major blues penatonic right?

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Syncopated tunes in 3/4 time can really sharpen you're counting/timing. Use a metronome to find your BPM.

as for the 12bar - Gmaj Pentatonic might work better. But the rule is: If it sounds good do it. :-)
If you get an electric metronome you can usually set it to what time signature you have in what you're playing...i find it helps a lot to be able to switch it
I would use E minor to get that "ballsy" blues sound. If you use Emaj it would sound too bright.
In blues it's common to use major chords and solo in the minor scale.
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