I'll try playing with the numbers a little later.

So going off what Stick and Red have said is there much of a difference between the play at 2/4 compared to 1/2? Or do you not notice much of a difference untill you get to the 3/6, 5/10 levels?

I haven't noticed too much of a difference between 1/2 and 2/4. Just keep playing ABC poker, and they'll keep paying you off.

I'm just starting to take shots at 3/6 myself, and haven't played 5/10 yet, so can't speak to the differences there.

Here's a hand I picked at random from a couple nights ago that shows what kinds of hands they'll pay you off with (no converters for this site) -

GAME #436612917: Texas Hold'em Limit $2/$4 2006-09-25 02:35:50
Table Celtic Manor (6 max)
Seat 1: honeyboy629 ($63.50 in chips)
Seat 5: yanpeng ($76.00 in chips) DEALER
Seat 6: lineker5 ($136.50 in chips)
Seat 8: snj4eva27 ($70.75 in chips)
Seat 10: stickdude90 ($275.00 in chips)
lineker5: Post SB $1.00
snj4eva27: Post BB $2.00
*** HOLE CARDS ***
Dealt to stickdude90 [[Qs] ]
Dealt to snj4eva27 [[As] ]
stickdude90: Raise $4.00
honeyboy629: Fold
yanpeng: Fold
lineker5: Fold
snj4eva27: Call $2.00
*** FLOP *** [[Qh] ]
snj4eva27: Bet $2.00
stickdude90: Call $2.00
*** TURN *** [[5c]]
snj4eva27: Bet $4.00
stickdude90: Raise $8.00
snj4eva27: Call $4.00
*** RIVER *** [[3d]]
snj4eva27: Bet $4.00
stickdude90: Call $4.00
*** SUMMARY ***
Total pot $35.50 Rake $1.50
stickdude90: wins $35.50

If you are playing well and being very diligent in your table selection a BB/100 in the 1.8-2.0 range is possible but I wouldn't put much stock in your numbers until you reach 100K hands or so. As far as moving up if you have the BR go ahead and take some shots at good tables. Just be aware that even when playing well you are VERY likely to go through some very serious downswings, particularly in the SH tables. I would recommend that you not play at a level full time in SH games with less than 600 Big Bets unless it is easily replacable or being very willing to drop back down in limits if things should turn sour. Continued good fortune.