Hello. Most antennas will work about the same, more important is how it's mounted and mounting location so choose wisely. Also make sure you check your SWR for match or if you know someone who can do this for you buy them a beer or two and get the best match you can get! That will usually do you a better job then the type of antenna.
As for PA speakers I usually just hop over to the local Radio Shack and pick up one of theirs. Biggest problem with CB PA's is they are very low power, mostly only a few watts so don't spend big bucks on one. If you don't mind replacing them from time to time or live someplace where they won't get to much bad weather I've used regular box speakers. They're usually cheap and will sound about the same as a regular PA speaker with the big horn. If you want to go big power you'll have to get one of the powerful amp's and speakers used on emergency vehicles. Will cost around $200 or so but you'll definitely be heard!!
2001 Dodge Ram 2500 4x4. Winch up front, service bed in back! Camper to follow!