I have a few questions about this 1996 S-10 Blazer 4.3L 4x4 2-dr with 194k miles I recently bought.

1-The heater core leaks and I want to replace it myself, but can't find any good instructions on how to go about it. For now I just bought a small piece of pipe and bypassed the heater core. I took of most of what I could of the dash from screws I could find but I can't seem to figure it out.

2-I recently replaced the water pump and filled it with water, I noticed a water leak from the top of the engine on the driver side. If I squeeze the radiator hose, I can see that it pushes more water and the leak is in the crevice of the intake manifold and the valve cover. I'm guessing this is probably a manifold gasket that needs replaced. This seems like it should be pretty straight forward to repair myself, but would like some advice.

3-The seller of the auto told me the a/c didn't work and that they thought it was the evaporator. I tried to charge it but the a/c compressor never came on. I emptied a can of refrigerant into it, but never got any pressure. I'm thinking that maybe there is a relay not working, but don't have an owner's manual to know where to start looking. I figure there is a leak since the can should have put in a little pressure.

4-I just noticed that I hear hissing coming from the front of the auto after driving it. I'm guessing this is a small leak in the radiator as I don't see any water coming out. Is there a way to repair (like with some "fix-a-leak" product or am I better off removing it and taking it somewhere or just replacing it.

5-When try to start the auto each day, it seems to have trouble unless I just barely tap the ignition. If I tap the ignition for just a second, it won't start the 1st try but it will on the 2nd or 3rd or 4th usually. If I crank it longer, it doesn't want to start and I've discovered if I pop the hood remove the air intake and put in about a tablespoon of gas, the replace the intake, it starts right up with a normal crank. Is this a result of the possible intake manifold leak or is it a sign of something else going wrong like fuel pump or filter?

Thanks much for any help.