Some
edict_t are indeed useful, like listenserver or worldspawn.
Clients
edict_t (Bots or players) is also obviously useful. These edicts can be acquired by
pfnPEntityOfEntIndex() (or INDEXENT macro), however I don't like idea of calling HL engine if we don't have to.
My question is, is it safe to keep these entities and use them within your plugin ? Of course every map change I shall update listenserver, worldspawn and remove all player edicts.
I don't know what could replace listenserver (acquired in
ClientConnect()) and worldspawn (acquired in
Spawn()).
Client edicts could be replaced by client indexes and every time I will need edict, I call
pfnPEntityOfEntIndex().
I shall think of "new client is here, add it to your list" in
ClientPutInServer() and of "client left, remove it from your list" in
ClientDisconnect() and on map change.
So is this approach with using edicts OK ? Is it safe to think location of edicts doesn't change as long as client is connected ?
(It really helps to understand the problem when you write everything down 
)