ok so i have the platinum now - took about 3 hours of play just about.
here is my guide to getting the platinum as easily as possible.
1. use the save, resigning obviously.
2. start up minigames, play one to get ''Ill try anything once''
3. start up story mode and change weapon to Minigun (the only weapon you will really need) and add a second weapon (doesnt matter which).
the trophies mentioned in the OP will pop:-
''

e-Generation
Decom-Poster Child
Dis-Figurine Collection
Graphic Horror
Boom Headshot!
Merchant of Menace
Fully Loaded
Yakuza
Be My Valentine, Jill
Perfect Victory
Do You Feel Lucky?
Extreme Hardcore''
4. Change the options to ''crosshair off'' and play level 1 (the challenge trophy will pop on load for each level) - make sure to kill the boss with 1 bar of life left. this will pop ''suffer like g did'' and the trophy for beating the level and also for beating any level with no crosshair. finally you will also get ''never runs dry'' as you cant run out of ammo!
5. Change the options put the crosshair back on for the remainder. start level 2 and that challenge trophy pops - this is the easiest level in the game IMO so getting goregasm and maintaining it for 2 mins wont be hard at all. also make sure to pick up grenades here and switch to second weapon (as grenades cant be used when using minigun) to get ''toasty''.
6. just continue with the remaining levels getting 2 trophies per level - at this point you should have 95% of trophies!
7. go to Directors Cut mode and replay level 2 - as its the easiest one. using minigun it will be hard to get hurt at all, and the boss is very easy too - completing this chapter without losing a life will net you ''Hardcore''.
8. Finally go to ''Overkill'' and complete the level, you can lose lives but you only get 3 continues, but it should be more than enough to beat Mother. This will get you the ''Lights, Camera, Headshot!'' trophy and of course the ''House Of The Dead Overload'' Platinum.
i actually did 7 and 8 the other way around but same difference.
i hope this helps!