Practicing at 80 yards is certainly great practice and it does make those 20, 30, and 40 yard shots a piece of cake. But I would never try to hunt with that many pins. My brain would short circuit trying to decide which pin to pick when a bull comes charging in. Shots at elk with archery equipment over 40 yards is pretty uncommon.
Yes about the speed. You can look at either the IBO or AMO speed ratings. The AMO is standardized and will give you a better number to compare different bows. IBO speed ratings are typically given with nothing but a tieed in nock on the string and nothing else. Also some manufacturers tend to inflate these numbers too. It is still a good indicator of speeds from bow to bow.
Excelent choice on broadhead selection.
Do not worry about how long your arrows are just yet. When you get your bow all picked out and get t set up for you the pro shop guy will have you draw the bow with an uncut arrow and mark and cut them to the proper length. A 30 inch draw does not mean a 30 inch arrow. I have a 30 inch draw but my arrows are only 29 inches long and that still gives me about 3/4" past the rest.
You do get what you pay for with arrow to some extent. IMO Carbon express terminator
select arrows are one of the better carbon arrows made. They will give you a finished weight of about 485 grains with three feathers and a 125 grain head @ 29" long. This is a very good weight and will give you a very good ballance between speed and available KE.
ACC's are an excelent shaft but will run you about $120 for a dozen. Gold tip makes a good shaft as do a number of others.
What you want to look for in a carbon shaft is...................
Straightness, I prefer to use shafts with a rating of +-.003" or better.
Matched weight in shafts. Some manufacturers will offer better matched weights within a dozen shafts. You should be aboe to find them within +-3 grains per dozen.
Consistand spine over the length of the shaft is another impotrant factor but few manufacturers actually publish this. Black hawk arrows claims +-.75 Newtons. What ever that means.
Many people like the camo arrows. I have yet to spook an animal with a black arrow and actually use white crest wraps with white and Flo. yellow feathers. Unless you want the added weight I would forget about it. I doubt the elk will care either way.
I highly reccomend feathers for fletching. They give you better FOC and stabilize an arrow much faster than vanes do. I use to shoot with vanes but since switching to feathers I get much better and consistand arrow flight.
Just a little side note.... With the bows you mentioned you should be getting better speed than Elknut too boot.