Can anyone help?

Having recenlty invested in a home CNC and got it talking to Mach3. I require some router bits to test cut and start working I guess.

Whats the difference with HSS and Carbide?

The collet in my router is 1/4inch and I have sourced some 12mm MDF and 3mm mirrored di-bond for test cutting. At this point I have no cutters and would like to order some for delivery.

Any advise would be appreciated.

Also, it is wise to invest in a collet reducer thus allowing the purchase on 1/8inch bits also for detailing work?

Finally, I have a 4th axis, not turning yet but does anyone know of a good supplier for a tail stock? Oh, whilst I remember is a t-slot table for clamping easy enough to build?

So many question. Thanking you all in advance for you wealth of experience, hopefully I will return the favour with some design/cad/modelling knowledge.