Here are some ideas that popped into my head
about the RP/I2/Pfed meth synth:

1. Why not freebase the ephedrine before you
do the reaction? Seems to me that this would
be the easiest way to purify the Pfed.

2. Will you get Meth HI instead of Meth HCl,
if so is there really a difference?

Well freebasing the e before you do the reaction is part of doing an acid bas eextraction if you do one, it is a very good way to clean your feedstock.

freebase e in the reduction works exactly the same, some say it reacts faster but that is an aside. You do initially get meth HI but it is bassified abnd re salted as HCl.

would it be all that bad to have a mixture
of meth HI and meth HCl? to me it seems like
there would be very little difference (kinda
like the difference between Na-GHB and K-GHB)
except for possibly the extra weight of iodine
vs chlorine (which is about an extra 100 g/mol).

Actually, it would be undesirable to use the freebase in rp/I2 type reduction. These reactions are usually designed to where an appropriate amount of HI is synthesized. This means that the freebase is going to use an extra molar amount (in a normal reaction, you need double the molar amount of HI to ephedrine, using the freebase you'd need triple). So yeilds will suffer greatly. You could technically still use the freebase, just increase the rp/I2 content to make the extra amount of HI. But this would mean scrounging up more of that precious and pain in the ass to get rp. All because you didn't use a salt. So by now you get the point.

Also, no you would not get a mixture of HI and HCl salts. Almost all HI reductions give you some meth HI mixed in with the meth HCl, but upon basification, the base molecule (in this case meth) is freed and the acid reacts with the base to make a salt. In this case, upon basification of the mixed salts, you'll get NaI, NaCl, water, and meth freebase. Whatever acid you use to crystallize the freebase with is going to be what makes up the salt in the end completely. The only way you'd get mixed salts is by using mixed acids to crystallize with.

you will at worst need more iodine using freebase isn't going to use any more redp it will just use more iodine. The redp is a catalyst for the generation of the HI.

but the RP does get used up to make the HI,
because it gets oxidized to a phosphorus oxide
in the process, doesn't it?

also, if you had enough HI on hand (how? don't
ask me), is the RP still necessary, and why?