Hi FrogsNPigs - welcome to AA !
If you definitely want angels you should definitely go with the 40Gallon tank, larger if possible
There are lots of good resources on the web that can help you.
The first one I'm going to recommend is on "fishless cycling". Cycling a tank this way allows you to build your "good bacteria" colony to allow the conversion of ammonia to nitrites to nitrates, which ammonia being the most toxic and nitrates the least. It will also allow you to add practically your entire stocking list once the cycle is complete. If you cycle "with fish" then you're in for a very long haul of adding one or two fish every few weeks with lots and lots of water changes.
here's the link to the article (it says its for saltwater but it works for freshwater also)
http://www.aquariumadvice.com/article_view.php?faq=2&fldAuto=15
The second one I'm going to recommend is a place where you can view all the types of freshwater fish that might be available to you. They list the water parameters (pH and hardness) that are in the natural environment for the species. They also list some compatible species, so you could look up Angelfish and go from there
http://fishprofiles.com
Once you come up with a list of fish that you think you're interested in post it in another topic and you'll receive great feedback from the folks in the forum
As for plants - that really depends on what type of lighting you have. You can grow a greater variety of plants under higher light, but then you need to consider fertilization dosing and potentially adding CO2. If you read the stickies in the planted tank forum you'll get alot of good information and you can post your followup questions there.
Sounds like you're going to have alot of fun with this tank
I wish you well and lots of enjoyment