Hand-rolling a CP/M machine

With all of this recent 8-bit and CP/M talk, it's prompted me to do a little digging on what it would take to put together a CP/'M machine on my own. I already have a couple of commercially-produced boxes. This is about taking a Z-80, some RAM, some ROM and a storage unit and making it run CP/M. I've been reading the various threads, so I have a general idea of what has to happen, but I'm still fuzzy on a few specifics, no doubt due to my lack of deep experience with the Z-80. The point of ROM vs RAM at $0000 has been gone over a few times. Do "standard" CP/M machines use a shadow-ROM technique, or what, to cold-start? We used to use a trick with the 68000 that would map ROM at $000000, _and_ at some higher address, with the first few instructions jumping to the higher ROM image, , and either an I/O pin that toggled the address mapping for the lower ROM image, or just watching for the first pulse from A23, such that the act of jumping up to the higher ROM address itself would remove ROM from the bottom of the memory map, revealing RAM. How did CP/M systems handle 64K of RAM? Was there one primary way it was done, or did every hardware vendor do it differently? I should probably just confine my efforts to 48K of RAM and use the upper 16K for a boot ROM, but if it's easy to support 64K of RAM, why not? To confirm, the minimal I/O system is some flavor of serial interface for console I/O (presumably piped to a display smart enough to handle ANSI codes), and some form of block-addressable storage with a CP/M filesystem, right? (I'm ignoring handy I/O like parallel printer ports and 8255-type GPIO and the like, for the moment) Is it required that the storage unit be writable? Is there a minimum size for the display? That wouldn't matter for hanging a VT100-equivalent off of the console port, but if I were to use some flavor of textual LCD, it would very much matter. To find another way to ask, would the body of extant CP/M apps freak out if you try to run them on a display that's under 40 chars wide or under 24 chars tall? Do they expect 64 chars wide or 80 chars wide? I don't think the OS itself actually cares how wide or tall the display is, but perhaps some of the CUSPs, like DIR, might. Rather than taking a bare Z80, wiring on a Z8530, an SRAM or two and an EPROM, I was contemplating beefing up my 1976 SDS Z-80 Starter Kit to the point where it could run CP/M. I've written about it here before, when I first got it, to remind those that don't know or don't remember what it is, it has a ~2MHz Z80, 1K of 21L02 SRAM, room for one more K, one 2716 with "ZBUG", two empty 2716 sockets (one attached to an EPROM programming circuit), a keypad and 7-segment LEDs, a largish wire-wrap area, and two S-100 slots. Presuming I wire the SRAM, a larger-capacity EPROM, and some serial device into the wire-wrap area, is there anything I should look for in an S-100 card that would be interesting to install? A video card (rather than a serial console), perhaps? I think I have one or two S-100 video cards, but I was never clear on how one attaches a keyboard to that rig - is there an ASCII keyboard port typically provided on an S-100 video card, or is that a separate peripheral? Thanks for any and all answers to my noobish CP/M questions, -ethan