We stayed there once a few years back for a training class there. Nice place.
But we'd rather stay right next door at the Marriott's Residence Inn. Awesome complimentary hot breakfast everyday plus "happy hour" meals during the week. Kids Suites if you need them. Very reasonable rates for Marriott Rewards Members and free parking. They also have a BBQ area next to the pool and full kitchens in the rooms. Since you are staying that long, you could easily cook some meals and "live" nicely in it. There is a Target right across the street as well as quite a few places to eat.
I don't know about the walk though. It is a long one, but do-able if you HAVE to. The terrible ART system has a pick up spot in front of the two.
Personally, we drive there (PAP parking) or use the other "benefit" that comes with being regular guests there.
Walking during the daytime is no problem at all. Plenty of folks do.
Walking around late in the evening or after midnite needs the usual cautions.
Actually, the only place that I know of that might be a problem is right there at the 7-11 store at Harbor and Katella.
For some reason, APD lets the hobo's hang out there 24/7. They continually ask for money and leer at the ladies/girls.
One of them tried to "convince" my wife to buy him some booze (I was waiting in the car with the kids). When I saw my wife give me "the look", I quickly put a stop to that nonsense (as she knew I would).