Intro. and stock philosophy questions

Hello. I just started trading a month or so ago. I am doing so in a Roth IRA. So there's my first philosophy question-

Based on my Roth IRA's tax free status, and it's long term time frame. (If I make a mill next year it's stuck there till I retire) I should focus somewhat exclusively on stocks that have a healthy dividend- right?

#2 So as to avoid trade fee's and as a long term diversification plan, is the following a sane strategy? Pick one stock, buy 1000 shares at a good price then sell 800 or 900 shares at a price that would give me the same cash I put in back to do it all over again with another stock.

Any thoughts on these two ideas would be appreciated. Thanks