for your proposed use, aim for the largest printer you can afford. Being able to print a full head sized object in one go means you won't have to chop it in pieces and glue it together after the print is done. On the flip side, if economy is your goal, consider that you'd have to chop a head sized object into at least four pieces to print individually, then glue them together.

PLA provides the easiest printing, but will distort if left in a hot motor vehicle. If you don't do that, PLA will give you good results, a variety of colors, lower temperature, faster prints. ABS is best used in a fully enclosed printer, but offers wonderful sanding results as well as acetone vapor smoothing for a glossy surface (with some loss of detail).

The Ironman project you've seen are probably multi-part prints with plenty of elbow grease involved after the printing is done. From a time standpoint, even thirty hour prints will seem short when you have two or three times that much work after the print is done.

Only someone who has completed an Ironman print can provide a ball park figure for the time involved.