The only advice I can give for BIAB is try not to direct heat the mash if you can help it. It creates hot spots (even with stirring!) that will denature enzymes and leave you with beers that won't finish lower than 1.020 or so. Unless you have a kettle with a thermometer on the bottom. I made this mistake on several beers. I tried pitching more yeast, aerating longer and better, mashing lower, etc. Nothing worked. Until the last one I did, I didn't touch the mash at all for 60 minutes, and the beer finished at 1.009. I thought I was stirring really well to eliminate those hot spots, but apparently not. From now on, whenever I do a brew in a bag, I won't direct heat, maybe only for mashout.