Using the ONLINE rebuild will reduce locking & contention but will increase tempdb use, so be read for that.

I wouldn't get too locked into particular time frames. It reall depends on the system. Some systems may only need indexes updated once a month. Some may need adjustments made twice a day. It really depends on data and the code running on your system. For example we have one application with a couple of tables that are, quite frankly, poorly put together. Due to internal issues we can't make changes to these tables at this time (don't ask). But, the statistics on the tables go out of data within a few hours. So, for just two tables, we're updating statistics once every two hours. It's a band-aid, not a solution, but sometimes, you'll be pulling doing the equivalent of slapping on duct-tape to fix problems in your system.