1. Yes. Theres 2 different products: HDLoader and HDAdvance, with both u need a network-adaptor and a IDE-HD that fits AND work (Maxtor hds are good). (Look in HDD section)
2. Yes, there are several non-mod ways of bootin' a backup dvd+-r/cd-r. Most of them requires some way of swappin' using SwapMagic v3 bootdisc or using a exploit on your memorycard (triggered buy a original ps1 game) to load software like hdloader/cd-loader ... either way u still need to be able to swap in your backup without the ps2 knowning (not pressin eject button). Most people use a fliptop or swapkey. (look in this forum and exploit forum)
3. Plenty chips (look in modchip forum). Best? Donno... Matrix infinity maybe ... some use a clip-kit (and some dont).
4. It depends on your ps2 ... some read dvd-r some read dvd+r and some read both (a bit like the Xbox). Some really old ps2's dosnt read dvd+-rs at all (maybe not even cd-rs?). It might be a region, media or laser thing My pal v50004 reads both and my old 3900X reads dvd+r best.
PSP 1.52 (DG), DS 001, XBOX v1.6B+Cheapmod+120GBHD, SM33, 50004+HDA10+120GBHD, SM32, BP11, 3900X, XBOX v1.6+Softmod, P4_2.666, GBASP, GBA,Celeron_700, DC, PS1, P2_300, TI85, Saturn, GBC, GBP, Megadrive, P75, Amiga 500, MS, 486SX25, Amstrad CPC464, ZX81