nick wrote
can I record something simultanously on the right channel if I make myself a splitter cable of sorts? 2 mono jack inputs to single stereo jack, one on each channel?
Yes. That's how it's designed to be used.
also the headphone output, realistically could I split it twice without losing volume or quality if I want two sets of phones on at a time? or should I rather get something like
this?.
Don't split it - that halves the impedance that the output sees and drives the headphone amp twice as hard as it's supposed to. A dedicated headphone amp is the way to go there, and the Behringer headphone amps are some of their better products.
just want something to mike up my acoustic then attempt to double as a vocal mike. currently using my ancient road battered carol mud525 600ohm dynamic mike for the job.
The best inexpensive all-round mic in the world is (IMO) the Shure SM57 - it's a jack of all trades and a master of a few. While you can do a lot better with specific mics for specific jobs (like vocals), the SM57 does at least a decent job on just about everything, and is one of the top choices for guitar amps and snare drums. So if you buy one or two to start out with they never go to waste - even when you have mics costing over R50K. They are also seriously road ready and durable so double as gigging mics. Definitely a huge upgrade from a Carol, however you look at it.
also, one of those microphone er screen things, will they stop the harsh P's and Bs?
Pop screens (or pop filters). They help a lot - also with sibilance (hissing on "S" sounds). Dynamic stage vocal mics like SM58s have them built in. You can buy them for a few hundred bucks, but you can make one with a stocking stretched over a wire coathanger (old studio trick ?) - not as pretty, but works just as well. Also experiment with backing off a little from the mic and singing into it at a slightly different angle.