1. Are water buffalo avaiable in July?

Yes, a good month for them.

2. Is a .338 Win adequate for them?

Most outfitters recommend a minimum of a .375 H&H.

3. If he would have too much trouble importing his rifle on this short of a notice is it a common practise to rent a rifle?

All GOOD outfitters will have a good quality loaner in .375 and possibly .458.

4. What would a decent outfitter or guide cost?

5 day hunt, including one buffalo trophy fee, up to US$8,000. Arnhemland is more expensive as buffalo numbers are higher and it is a true wilderness hunt. Station (ranch) hunts (free range) can be cheaper but less choice for a trophy.

5. What other species are available in July?

Wild boar, banteng (Asian Wild Cattle), scrub bull (feral cattle), camel, donkey, feral brumbies (horse) in the Northern Territory.

In the rest of Australia, a long list including many species of deer.

6. Other than a passport what else does he need? i.e. visa, shots etc.

No 'shots' required. I believe US citizens do require a visa. He may also (or may not) require a temporary firearms licence. I am unsure of the NT's requirements for a hunter NOT bringing his own rifle.

A number of outfitters to consider. All are members of NitroExpress.com.

Arnhemland Water Buffalo and other game in NT or Australia-wide:

Matt Graham - Hunt Australia

http://www.huntaust.com.au/

Graham Williams - Australian Buffalo Hunters

http://www.biggameaustralia.com/

Scrub bull and boar in Far North Queensland also enquire about buffalo

Alan Moon - Alan Moon Safaris

Alan Moon Safaris

Check out my story on hunting buffalo here and also Craig Boddingtons, here

Also this recent thread Outfitters in Arnhemland.