Yep transfer from another state is the same as deregistering and registering. You will need both a mod plate and RWC.
Here is the list of QLD Mod Plate codes:
You are definitely going to need an LA1, possibly LA3 for the 26/30.
Others may be needed depending on other mods you have, and what scheme the car was complied under. If you don't have the compliance papers that will be the biggest headache, the rest you can all get around. If QLD transport decide it hasn't been complied properly and you can't prove otherwise, it will have to be complied again.
Mod plate guys charge what they like, and they all do it differently. Some charge per plate (set price, $300 for example), some charge per code, and others charge a large amount for the first code (say, $100), then not so much for each code after that ($50). In any case, you wouldn't be looking at more than a few hundred bux at most.
Some places will look closely at the car/mods and fail dodgy things, some will look 'less thoroughly'. You will need one in the latter category based on some of the things you've listed (more info below).
Yes, you will also need a road worthy certificate (RWC). These vary in cost too, I think around 100-200 bux (ballpark) and again there are ones who are 'very thorough' and ones who are 'not so thorough'. As a general rule, the more expensive ones will be less thorough . Technically, these don't cover modifications but are about making sure the car is road worthy (brakes work, suspension works, not falling apart due to rust, etc.) but they can still fail you for illegal mods if they notice them.
In regards to your mod list:
rb26/30
Will be OK with mod plate.
intercooler holes under battery tray
This is illegal, but if your mod plate and RWC guys don't look to close it won't be a problem for getting rego. If the buyer gets pulled over by the fuzz though and they spot the holes, he will need to convince them that they are factory holes or he'll be in for a very hard to clear defect. FYI, this is considered cutting a 'structural part of the car'. Stupid, I know.
reo bar slightly modified for front bar.
Depends what you've done. If you've cut it, see above, although it should be easy to clear this defect with a stock reo.
If you've just bent it slightly or something, it should be OK.
bigger wheels
OK as long as they fit the rules set out here: http://www.tmr.qld.gov.au/~/media/c792a0c9-92b1-43ee-933b-7bdd8b20842f/pdf_modification_motor_vehicles2.pdf
1000cc injectors,
2x 044 fuel pumps
OK as long as the aftermarket ECU controlling them is nice and hidden
3.5 straight pipe with muffler, no cats.
No cats is illegal and a MASSIVE fine if caught.
Striaght pipe + Muffler will be OK if it isn't too loud. Suggest putting cat(s) in.
screamer
Illegal. Again, will be possible to get past mod plate and rwc if they don't look to close, risk of defect once registered though.
You can't get mod plates to cover any of these problems, they are just plain not allowed.
In short, if the compliance is all in order you should be able to get it registered, but driving it round will risk defects. One of the joys of owning a modified car in any state.