In my experience with keets having pasty butt it is usually caused by incorrect temps (usually too low, and also from the stress from having a rough time during shipping)... but since you hatched these guys, the brooder temp may be the issue so make sure they have a temp of 95 degrees under the lamp, measure the temp on the floor by laying a thermometer directly under the glow. If they are huddling, they may be cold. Are they noisy? Noisy keets are usually cold keets. A larger brooder might help them from piling too, with the heat at one end only so they can find their own comfort zone.
Pasty but can clog up and kill the keets if you don't remove it... Carefully soak off the poop with a warm wet cotton ball, pat the area dry and apply mineral or even corn oil to the vent area to keep more poop from sticking. Then keep an eye on those keets until it's no longer a problem. Toxins will build up and can kill the pasty butt/blocked keets quickly.
As far as bedding goes, keep using the old towels if possible, change them as often as you can. They really do need good footing the first few days while their legs and feet are still developing and strengthening (I use rubberized shelf liner and change it 2-3 times a day for the first 3 days or so... but yah, it's a lot of work!). They will become more active in the next couple of days and then you can put them on coarse straw as long as you see them eating and drinking well. But I would definitely avoid shavings for at least 2 wks. Chances are they will eat them now, and can definitely die from that..
Splayed legs will not go away, and will only get worse if not corrected. The hip joint has been injured and stretched allowing the leg to splay out, you will have to brace the keet's legs to hold them correctly in place, the correct space apart, ASAP. The longer you wait the less chance you have of fixing the keet. Compare the distance the legs need to be apart with a normal healthy keets. I use a strip of vetwrap, some use regular band aids cut lengthwise, some use pip cleaners... but If you do a BYC search for splayed leg, it will pull up several methods to try. Usually a keet with braced legs needs a little extra help learning how to walk with the brace on, and should be braced for 2-3 days or until the brace comes off and you see the keet walking/running as normal. You also want to make sure it's able to eat and drink... you may have to dip it's beak several times a day to make sure it stays hydrated until it learns to cope with the leg brace.
Good luck, hope that helps!
