Oh wow...I just got back to the Big D recently myself. Dallas is AWESOME.
Unfortunately I don't know anything about the hotels around DFW since I never had to stay in any of them but there are TONS of hotels/motels in the DFW area....search for them in Irving, Grapevine, east Fort Worth, north Arlington, and the H.E.B. area (Hurst/Euless/Bedford) if you want something that is only minutes from DFW. Be aware that depending on the time of day he arrives, you may encounter extremely heavy traffic.
In terms of highways...121, 183, 114, and 635 are the major highways that run near the airport. 183 is sometimes called Airport Freeway, 114 is sometimes referred to as John Carpenter, and 635 is also LBJ. Apparently the DFW airport property is larger, square-mileage wise, than the island of Manhattan...so it's a biiiiiiiiiiiiiiiig place. 121 is a pay road through the airport and 161, aka George Bush Turnpike, is a tollroad. 183, 635, and 114 are freeways.
As for the POE at Dallas...I've been through immigration in Dallas a few times and it's unlikely they'll have anyone there who speaks Magyar (that'd be unusual anywhere) but I'd guess they are used to dealing with immigrants who don't speak the language very well and it's probably nothing they haven't seen before. If they do have to bring in someone it could take a while for them to rouse a Magyar speaker; those are pretty rare!
As for the no-frills aspect....please be aware that some areas around DFW can be pretty rough. Irving south of 183 can be dodgy and the area of Irving where I once lived...near 161 and Beltline...has gone into a gradual decline and some streets/apartment complexes have become pretty dicey. Some of the motels around the airport are actually mainly housing for people who can't rent an apartment due to credit problems or bad rental histories so keep this in mind and BE CAREFUL. It's not exactly 'tha ghetto'...there are much worse areas in DFW...but it is definitely not a well-heeled area directly east or directly south of the airport.
You might want to consider a hotel a little closer to civilization.

If you must stay near DFW, try this link:
http://www.expedia.com/pub/agent.dll?qscr=...4856711290&