Difference's between PS3 and PS4 versions of BF4

EA,

Please could you please detail the differences between the PS3 and PS4 versions of battlefield 4, there are several different reports out there saying different things. I bought the PS3 3 months ago because this game would be available and it meant I could get practice in on BF3 before release. I have pre orderd BF4 and eager to receive but I have a PS3 and starting to regret buying a Ps3 and Bf3 as now i can't afford the PS4.

- My friends are significantly better off than me and might end up with PS4's - will I still be able to play with them?

- I've read that the maps on PS3 are limited to 24 but the maps on PS4 are at 64, is this a long term difference or just a starting limit to test the servers and console capacity?

- I've read that only on the PS4 will you be able to use a tablet as a split screen, if PS3 are playing with PS4 wont this put us at a distinct disadvantage?

The above are just a few of my focal points to try and show my question more clearly, just need to know the difference between the versions and compatibility issues

Thanks