Silky, let me clarify on the springs for you: Lowering springs are bad, REGARDLESS of which struts you use. So if you want the springs, a better strut won't help them. The problem is more basic. They have too much drop for their spring rate. It is a spring problem and nothing you do with the struts will help that. To fix the problem, you'd have to have less drop (something more stock looking) or more springrate (basically a racing hardness which would also require much better than factory struts). Lowering springs are safe in that they won't cause your car to explode, they'll just decrease handling performance and ride comfort. They're "safe" (except for something like S-Techs, I think they're beyond what I would call safe).
225/40r18 are what I would call a "normal" width for the WRX sedan. They are usable even at an extreme wheel drop (assuming a reasonable wheel offset, which +48 is). You can go wider. You'd need at least 8" wide wheels to do it but 235 is a very good width for your car. 235/35R18 is a little thin in terms of sidewall, most people who go 235 go with 17" wheels so it's 235/40R17. 235/40R18 or 235/45R17 I would recommend avoiding at all costs for an EJ205 powered car like yours. You want shorter than stock, not taller.
Will the setup you described rub? No. Will it improve your car's handling? No, it will decrease it substantially. Your mom will also yell at you if she ever rides in the passenger seat on a public road.
2015 STi: Still Stock
04 STi, 04 WRX: SOLD