Intarsia(?) blues

[luckyturtle.livejournal.com]

I'm trying to make a blanket as a present for my mom. my problem is I'm trying to do a block of cream in the middle surrounded by a blue green border. basically like the swatch, but much, much bigger.
This is a quick swatch I whipped up to try out the intarsia thing, check my colors, stuff like that. I'm a new knitter and it's obviously rife with problems (like that lovely dropped stitch in the stockinette that I discovered five rows later and was too lazy to fix 'cos it's a swatch, and the ugly row where I switched from the cream back to the greenish color on the wrong side).
questions:

1) I think I have the hang of the twisting colors on the back side when switching colors across the rows, but I have a few questions. I'm doing the green in garter stitch and the cream in stockinette, so on the back side when I switch colors, it's something like this: green in front of needles, k3, bring green behind needles, twist with cream, p7, twist and bring green to front of needles, k3. Is that right? it seems logical that you must keep the twists on one side, so switching from front to back of needles must happen however it works so the twists stay on one side. but I'm also one of those people that locks the door, turns the knob to make sure it's locked, gets in the car, runs back to check the door again, then goes back to the car drives a few miles then hope that I locked the door.

2)when I knit across the top, once I'm done with the cream/stockinette, other knitting in the right direction to avoid the crummy weirdness I created in that row of the swatch, is there anything special I need to do to make sure the green and cream threads are nicely connected to eachother? I'm trying to do this nicely and avoid knots, if possible.

and 3)my tension seems way different for my stockinette versus my garter stitch, what can I do to make it more even?

Thank you for taking the time to read this, and for any wisdom you may share. I will make this blanket, I will! crossposted. sorry.