Ah, I had the same problem when I first got my EZ-Flash IV. I can't remember off the top of my head but there's a program you need to use to transfer the files. I'll look around and I'll get back with you on that. It's an easy fix so no worries. I'm glad you finally got it, RNGing on Emerald will be a million times easier now trust me you'll wonder how you ever did it before :P
I was having some trouble with RSEDecode too since I use Vista (it kept crashing whenever I opened it). I finally managed to get it to work though - follow the EXACT steps in this video http://www.youtube.com/watch?v=Leso9t4g8zY including having the monster.dmp file in the same folder. Make sure you run Command Prompt as an administrator, though.
The way I find IVs and check PIDs is with RSEDecode (which has given me the right info 100% of the time); it's the only reliable way to check egg PIDs and IVs as well.
Yup that's the exact one I have :) but I get all my stuff from here: GBAtemp.net
It's a reliable site so no need to worry about that and it's a bit cheaper anyways ;) and I totally understand your reasoning which is the reason I do the exact same thing. Go ahead and buy they and your set to go :)
Well for the process of transferring from the 3rd Gen game to the 4th Gen there's a number of ways to do it. They way I do it like I said before is with an EZ Flash IV which ONLY plays GBA games, but since a 4th Gen Cartridge won't be able to read the game directly from the EZ Flash I have to trade from the Ez Flash to an actual 3rd Gen cart, then from the cart I can Pal Park the Pokemon to my 4th Gen cartridge. The way you stated wouldn't work because an R4 can only be played on a DS and DS's can't trade with GBA nor GBA SP's. So the only way to do it with a Flash Cart for the DS is to use DS the DeSume DS emulator which can Pal Park straight from a 3rd Gen save file, then from there load the DS Pokemon Save file onto a DS Flash Cart and trade from there to the 4th Gen cartridge you use as your main one. Either way is pretty simple. Let me know if you need me to go into further detail :P I know it may sound complicated.
I don't even fully understand it yet. Alternative spreads is just what I always land on...which is weird O_o...and yes that's the way I do it. I have an EZ Flash IV so I trade from there to an actual 3rd Gen cartridge and then I just Pal Park from there since the DS can't read the game straight from the EZ Flash. Another way to do it is to use DeSume and just Pal Park straight from the save file on the emulator.