LOL, I can literally see you swagger your way in here.
INF is not online capable at this time.
It is supposed to be a realistic as possible, team-based military mod. Since you come from SF I'll try to explain the differences using SF as a referrence.
First of all, there is no crosshair. This is the biggest peev most people have with INF. Instead of a x-hair, you virtually shoulder your weapon and use the ironsights or attached scope. For the average DM gamer this totally screws up the view coz a lot of your screen is blocked. This is perhaps the only unique thing in any game that can be found.
Stamina and damage - at this time, stamina in INF and SF are virtually the same. Damage as well, there are simiarities in that you'd need only a few bullets to kill a target where ever you hit the target. This will change in coming releases.
Weapons - the hallmark of any realism mod is its selection of weapons. All I can say for existing weapons and weapons that are planned is that you'd find them in almost any other mod. The weapons' implementation is very different however. The sounds, animation and texturing take real life in consideration - no teevee gun-shot sounds etc etc. Additionally, the use of these waepons, as I have already noted in the first paragraph, is very different. NO CROSSHAIR! Some people find it difficult to get used to.
Loadouts - instead of purchasing and equiping weapons on the field ala SF, INF troops deploy fully kitted. There is no rush to purchase or gear up. There is no station where you may purchase weapons and kit and have to do so before entering the game itself using the loadouts menu. In future versions of INF, when you kill an opponent, he will drop his back-pack and you may scavenge equipment and ammo from it. At this time, the stuff just drops out all over the place as in normal UT.
Gameplay - at this time, gameplay focuses mostly on team-DM. Team-dm, DM and assault maps have been included in the map pack. There are numerous aspects that are effected by INF's gameplay mechanisms. You move at a speed that a CS fanatic of mine regards as "constipated" - you walk just as slow as you do in SF and have the option to run. The difference is that in INF, tactics and strategy is focused on more due to the game mechanics of player speed, weapon aiming, map design and use of available cover. INF has leaning, and proning - I hear that SF has caught on on this good idea. With leaning and proning, cover is used more effectively and this simple tactic can be a most decisive action.
Bot support - at this time, playing with yourself - that is with bots, is the only option with INF. Its good practice and I find my bots tend to give me a run for my money. I think INF bots are a lot better than TO bots. I'm not sure of SF's tho since I havent played it in a while.
Maps - maps break or make a game, and INF's maps are the creme of the creme. Optimized for realistic play and with the INF game dynamic in mind, INF mappers bring you the cutting edge of maps to be found almost anywhere on the net. To me, SF and TO maps are great but INF maps when played with INF just blows the competition. Not to say that SF and TO maps are bad, you can play those maps by making a few changes actually - but some think it sacriligious ala BlackKnight or wuz it bloodknight?
What else would you like to know? Reading the roadmap will only give you a general idea of how INF is going to turn out coz its very very very outdated - and I think the team wants it to be so.