There are definitely certain cigars that you can save a lot by buying in Cuba vs the online retailers. The new QdO is one example of being pretty cheap in Cuba compared to online. You can get a great deal on Upmann Sir Winston if you find some. Many other boxes are drastically reduced in Cuba, just have to know prices and what you like. If I were you, I'd create a list of cigars that you are interested in after comparing the price list vs online retailer prices. I personally would look for boxes that are much cheaper in Havana, harder to find cigars, and/or custom rolls.
This is a good price list for what to expect in Cuba:
http://yulcigars.blogspot.com/
Regarding your "fresh" question... yes many of the boxes you will find will be pretty fresh, but you can also find some boxes with 2-3 years on them if you're lucky. That isn't the norm though, but depends on what cigar you are looking for. Some people like fresh cigars so if I were you, I wouldn't even have that thought in mind when buying. Would you want cuban cigars, or no?
Something else to keep in mind... as said above, only buy in the LCDH shops. When in old town Havana, go to Partagas or Hotel Conde de Villanueva. I personally would not buy singles either, only boxes. You just never know what you will get when buying singles and if you're not very educated on what to look for, well... Odds are you would be fine in the LCDH shops, but even then, not 100% safe. If you want to buy/smoke a couple singles there, pick wisely in the LCDH shops, you should be fine. Or better yet, smoke a couple custom rolls from Reynaldo at Conde de Villanueva.