Bred heifers seems an odd choice to me. This would give you all the hassle of calving with inexperienced cattle, potentially losing many calves and some mothers. Lots of potential for loss there. I would imagine you would not keep them for more than a few months, so this would be quite stressful for a new mother, increasing chances the heifers would reject their calves.
I would think feeder calves would be a better option, grow them out to butcher weight on grass and hay, then they can be sold as grass fed/sustainably raised
beef, which I understand can get a pretty high price. You would have to put in the work to market them but would avoid the risk of calving heifers.
The commodity beef market is saturated, so for profit you need to do something a little different and
sell directly to consumers.
Principles of pasture rotation are; smaller area allowed and moved more often is better. Each bit of
land would only be grazed once or twice per year. Your best tool would be portable
solar charged electric
fence. The
fence posts can usually be stuck in the ground with one hand.
For more ideas look at Gabe Brown who raises cattle and crops in one of the Dakotas. And
Joel Salatin who raises all of the typical meat animals in a rotational system.