First of all welcome ot MOL.
My next questions is are you planning to do this by hand or DA polisher? A DA polisher will always net you better results than doing it by hand. You have the right idea by washing and claying first. One other suggestion is to add a couple of the yellow foam applicators. They work great for applying waxes.
Out of these two I would get ultimate compound. It does sound like you have some stains and deep scratches. Ultimate compound will be my recommendation. But be warned up front that those stains could be etched deeper into the paint where a DA will be the better option. By hand you can make them less of an eye sore. Same thing with the scratches. If they are deep and you can feel them with your finger nail, then a compound will not remove them. Only fix is a repaint. Pictures are always helpful as well.
Both products are definitely worth it. They each have their place. Both can be used in between washes to give you that just waxed look. Ultimate quik wax will be the durable of the two. It's not a bad idea to carry a bottle of ultimate quik detailer in the trunk for those times where something gets on the car such as a bird bomb. Ultimate wash & wax anywhere is also great. It's a waterless wash that you can use when you don't have time to do a tradition 2 bucket wash. As long as it's not too dirty. I definitely recommend picking up many supreme shine microfibers as well as a couple water magnets.
Good reference video among others.
http://www.meguiarsonline.com/forums...in-Your-Finish
It's not a problem to go all Meguiar's. A majority of my products are Meguiar's. They are all made to work together. For the most part Meguiar's carries most products that you need. If they don't have it then there is another manufacturer that makes them.
The most important thing is to have fun and enjoy the results.