Does the speed3 bar FIT? Evidently, yes.
Does it stand to reason that any aftermarket bar will fit the front?
Should HD links be added up front with a HD bar?
*Likely Yes
*No, not necessarily. speed3 guys have issues with some bars, not all bars have the same bend in the arms. Some bars are known to have interference with the control arm. More of an issue with lowering, so if you aren't going to lower (as you mention), you may be able to run a bar that would otherwise cause issues.
* Maybe. If you are not lowering, and you are using the ms3 bar, you can likely get away with stock links, though you will be putting more load into those long, thin, stock links. If you are lowered, aftermarket adjustable links may be necessary. If you are running stock springs and aftermarket FSB, I would think an upgraded link would be highly advised simply due to the soft spring, big bar, and long, thin sway bar link. With soft springs and big bar, there is going to be a lot of force going through those links, a lot more than they were designed for. I think you'd need a HD link for that reason, if not for length adjustibility as well.
I will be adding a rear bar, not too stiff though, it's a daily driver. I will also be adding new shocks/struts (brand TBD). No coilovers. Came with 205/50-17 pilots. I'll plus zero when done. NOT lowering! I installed a Curt hitch last week.
I have not had the opportunity to drive the 5 that hard yet (purposefully find the limits for the factory setup. Ie: lose control) to make a decision on future setup.
I agree 1000% (not a typo) with PhunkyB - do not add a stiffer than stock FSB unless you also add a even-stiffer-yet RSB. You will be adding understeer to a car that already understeers.
IMO it makes no sense to start changing things before you've even driven the car and don't know what it feels like. (maybe you're just here doing research as a "what-if" scenario, but it sure seems like you're already pretty much decided what your upgrade plan is) Go do an autocross or two at minimum before you start buying parts, let me know if you don't struggle with understeer and traction coming out of corners - a FSB will make both of those things worse.