a) Unfortunately there's no way you can put a value on these values for certain parts of the game, simply because it will depend upon your playing style, your other base stats, and good old fashioned luck. The fact that you mentioned that monsters tend to flee all the time is the best indication that you should really be moving on. If it is really hard in a new area (and I mean you're getting flounced), you've probably wandered too far. For the time being you shouldn't explore the Western part of the map until much later on in the game. If in doubt make sure you have the Exit spell on one of your characters, and Exit out of a dungeon if your HP/MP is starting to wane (about 25% of their value).

b) End game stats...again, hard to say, since we don't know what sort of characters you're creating. Generally speaking, it's relatively easy to max out your MP (999). It's not necessary, but it's easy enough to do, so why not? HP is a different matter. You could probably get through the final dungeon with about 2k if you were careful. 2500-3000 and you'll have an easier time. 3000-4000 it'll be noticeably easier, and 4000+ will be a cakewalk. This is assuming you have plenty of MP and a high level Cure spell available (it's seriously worth having every character equipped with a Cure spell from as early as possible. It may knock down your Strength when used in battle, so be sure to level it up outside through the menu screen primarily).

c) Unless you want to go exploring that area I talked about earlier to the West, then you're out of luck. If you can survive the groups of Ogres/Wizard etc., then they'll drop plenty of spell books for you to sell.

d) Some people say FF2 NES is impossible without using the select+cancel cheat. Those people are spineless and weak. You can quite easily increase your weapon skills naturally. Later on the game if you want to increase them rapidly, then equip the lowest form of that weapon type, have a Blink spell handy, then go up against an enemy with very high defence (any of the Flan type's will do, but Dark Flans are the best since they have the highest defence). Then have Blink cast on the enemy as many times as possible, until your characters are constantly missing. It still counts towards your weapon experience amount. Then just do it for about twenty~hundred rounds (depending on your weapon skill), then finish them off with an offensive spell. Chances are that, with Critical Hits, you'll finish them off with your physical attacks before you need to do this however.

That's pretty much all the advice I can give. Good luck.