Dead Rising 2: Case 0-survivor locations

They shouldn't follow you. That's extremely weird. They also have side missions you can do for them for extra money and they'll be happy in the safehouse.

You get Katie some Zombrex then go and save Dick and then you will unlock the survivors in the Bar which you get $15,000 for. (If you do the gem side mission you get another $15,000). The other missions are triggered either by time or by your possession of the bike parts. If you do not have the bike parts then the next survivor mission will start at around 3:00pm, that is the two women in the bowling alley (Make sure you have Zombrex because you will need it for one of the girls in the quarantine zone). The next mission is around 5:00pm. This is where you get the handlebars for the bike, you need to trade a broadsword for them (You can get them in the hunting store). The last survivor is Bob's daughter and you need to be fast for this one because it Triggers at 7:00pm which is when Katy needs her Zombrex. You have 6 minutes to complete this survivor mission and get back to Katy. You can trigger the first survivor mission before 1:00pm if you have all the bike parts apart from the handlebars. Then you get the achievement "Still Creek Savior".
For those of you who don't know, here are the bike parts locations:

Wheel - Purchased from the shop for $5,000

Engine - Found in the alley behind the movie theater

Gasoline canister - on the floor near the gas hoses outside the gas station.

Handlebars - Given by one of the survivors behind the department store

Bike Forks - Found in the South East part of the map next to the big fountain. You need the key which is on the top floor of the hotel, you can get there by going down the alley next to where Bob is shooting from and jumping on top of the green garbage bin, from there jump on to the metal stairs climb up and go inside the door to your left. (There are a few zombies there and the key is in the room at the end on the left as you come in.)