For distribution feeders, we normally use Very Inverse or Extremely Inverse for Phase. Very Inverse or Moderately Inverse for Ground. Extremely inverse curves should be a little easier to coordinate with downstream fuses. Very inverse may work better if you have a lot of line reclosers or pad-mounted interrupting devices. YMMV.
The load mix really doesn't play much of a role when it comes to fault protection, other than cold load pickup issues.
You'll have to educate me on what you are referring to. Long-time and Short-time are associated with low voltage breaker trip units in my mind. Are you thinking about fast and slow recloser curves? Reclosing philosophy is a related but different issue and is somewhat regionally specific. We don't get much lightning so our normal reclosing sequence is one "fast" and two "Slow" operations.
In today's environment customers will complain about any reclosing operations.
Most of the reclosers are using a cooper form 6 controller which has I guess you could say a different standard of time-current classification then ANSI or IEC published covers, at least it seems that way. Curves are classified by number, although some of them are near identical ANSI curves, others appear to be modified versions of them for different protection schemes.
I'm familiar with the Form 6 and the old recloser curves. The numbered recloser curves date back to the old Kyle hydraulic reclosers. Cooper has continued them for legacy considerations. The Form 6 can also do standard IEEE curves. The main consideration is coordination with upstream and downstream protective devices, not so much the name used for the curves. You'll also need to decide if the goal is "fuse saving" or "fuse clearing" in order to pick settings and curves for the "fast" and "slow" curves. Do you have reclosers in the substation or breakers with relays? For substation breakers, the "fast" curve is generally just an instantaneous trip with maybe a short definite time delay (if you are trying for fuse-saving).
Without detailed knowledge of the system, we can't really provide much in the way of specifics, just general considerations.
The substations are breakers with relays, however the lines have reclosers (form 6 controls) in series. Fuse saving is done generally down toward the "end" of the line at the last recloser or, if a lateral requires fuse saving, a recloser is placed right after the trunk line tap. Trunk segments as well as the feeders leaving the substation do not utilize fuse saving curves, only 1 or 2 attempts at re closing since momentary interruptions can not be tolerated with commercial customers.
