5 thousandths of lift is not going to effect the tune that Allen sends you. Not a big deal.

Yes. The new cam will go in the exact same way. To be safe, run by Home Depot or Lowe's and grab some wooden dowel rods--5/16 and 7/16. Grab two of each. You can shove those (whichever size fits the best) in once you get the cam plate off. The only thing to worry about is the lifters--and you will take care of those with the dowel rods.
Once you get the valve covers off, take the rockers and rocker cradle out. Then make sure to remove the pushrods. Then move to the front of the motor. Remove and drain the radiator, CAREFULLY remove the c-clips that retain the tranny cooler lines. Then remove the water pump. Remove the crank pulley with a 3-jaw pulley puller. Then remove the front cam cover--there is a wire loom bolted to the bottom-right side of the block. You have to remove that 10mm bolt and get the wire loom out of the way to access the 2-10mm bolts on the bottom of the cam cover. Once that is out of the way, remove the 3 bolts on the cam plate. Then align the timing dots on the cam gear by putting the crank bolt back in (do not tighten with wrench) and turning the crank to where the timing dots line up. This is essential!!! Then CAREFULLY tap the end of the wrench with a hammer to loosen the crank bolt, being careful not to move the timing dots you just aligned. Then screw in 3 water pump bolts into the end of the cam and spin it around a few times, listening for the lifters to stay in the up position. Then spin the cam by the waterpumpbolts slowly--making sure you don't hear a click of the lifters hitting the cam. This is where you shove in the dowel rods--cut them about 6'' longer than what you think and then shove them in. You will need a pair of pliers to get them out. Make sure you push them in all the way to the back of the block. Once you have done this--CAREFULLY with two hands, slowly pull the cam out. Once it is out, pour some new oil on the new cam and slide it back in CAREFULLY. Do not bump or hit the cam on the block. It takes some finessing, but you'll get it. Then reinstall the cam gear and timing chain, making sure the timing dots are still aligned. If they are aligned correctly, then key on the end of the cam should be in the 3 o'clock position. Then reinstall everything in the reverse order you took it off.