76 Ski Tique Impeller

The old impeller should slide right off----maybe with some resistance depending on age/how long its been there---but just pull it off using needle nose pliers if you have to. Make sure to clean out the inside of the pump if it needs it (use emery-cloth if needed to help in getting it clean and smooth. Rough edges inside the pump bore will eat up the impeller in a hurry). Lube the inside of the pump, and the pump vanes, with white grease (Lubri-Plate works great----or any marine grease will also work great too).
When putting the impeller in just try and have the vanes already folded/flexed in the same direction as the pumps rotation will be and that too will give it the best chance of no problems on start up.
The pump shouldn't need to be primed (as it normally isn't primed each and every time its put in the water so this time is no different-----they have lots of suction and can collapse a normal type hose if its not one that's internally reinforced.
One suggestion in all if this is to get one of the premium type impellers that can be run dry for up to 15 minutes without harm. They are made of rubber thats more like hard silicone than rubber and work really well. Cost about $10 more but are definately worth the extra $.

No, you're fine. I don't use any grease or other lube, some types of lube will attack the rubber and shorten the life of the impeller, or stiffen it. I just make sure everything is clean, put the impeller in, turn it by hand in the correct direction to "set" the vanes in that direction and make sure all is good, bolt it on and start it up.