Yep, stuck float, and the overflow tube (brass tube sticking up in MR's pic) must be stopped up, so when the carb filled up with gas, instead of it running out of the overflow tube and onto the ground, it filled up your crankcase with gas.
So take the carb off, clean it, put a Shindy carb kit in it, and put it back together. That SHOULD fix your leaky carb. Make sure the overflow is clear, and if the float sticks again you'll get a tell-tale puddle of gas on the ground under the wheeler instead of a crankcase full of gas.
It will not steer easily being a full time 4wd machine. You can buy a Wide Open 424 disconnect for it, which replaces your factory front driveshaft with a cable operated selectable front driveshaft, and allows you to put the machine in 2wd.
You can also swap in an 02-04 front diff, which has an electric actuator in it. That will require the 02-04 front diff, front driveshaft (which will have to be shortened about an inch), and a switch, which will have to be wired.
Either way you will have a MUCH easier to ride machine. While you're at it, you might look at adding disc brakes up front. You can either buy a conversion, or get knuckles, hubs/rotors, and calipers from an 05-11 Foreman, 05-14 Rubicon, or 06-19 Rincon and put them on there.
The 450's are the last of the really bulletproof Hondas IMO. They lack some creature comforts that the newer ones have, but you can add creature comforts to a 450, and once you do you will have a really tough bike.
2005 Foreman Rubicon Camo
Perfex, 27" Mudbugs
Heated grips and Thumb , HID's
5K Viper Max winch
2009 Foreman 500FM Green
Perfex with HL springs
27" Execs on Rubicon rims
Heated Grips and Thumb, HID's
4K Viper Max winch
2006 Foreman 500FM Green
28" Mugbugs, stretched, Perfex, HLsprings
3K Superwinch winch
2009 475 Rancher AT Tan
26" Mudbugs on Rincon rims
Warn winch. Foreman pod light with HID, SRA gear reduction