Yes, if you go -5 with minmatar you will not be able to enter their space without the faction police shooting you. If you are in a fast ship that doesn’t really matter though as the faction police are pretty weak…and they always web before they scram so they help you get into warp faster.
It’s possible to repair standings via fleet turnin’s if you get that low…but it will take a LONG time to repair a faction rep of -5.
Not sure what you are talking about corporate alliance warfare.
Its not hard to repair faction standings. Just cumbersome or expensive depending on how you go about it. As long as you are above -2.00 you are safe to fly without being shot at.
If your only concern is reaching trade hubs (thus not entering their territory for other reasons such as ratting, exploration, mission running and so on) of factions hostile to you (or you hostile to them ) then you can use an alt to buy stuff at trade hubs and haul back home to your main.
When you enter Minmatar space with a Minmatar standings lower then -5, the Minmatar faction police will appear on your grid with a 10 seconds delay wherever you land… which is enough for you to warp off or dock up in most cases. Once they arrive, it will take them 5 seconds to aggress on you. The faction police doesn’t shoot at capsules, so you can pod through Minmatar space on autopilot if you want.
The faction police also interdicts your cloaking device, so you cannot insta-warp to an undock bookmark and cloak there, or cloaky MWD align out of a gatecamp (including one staged by the faction army)
The main problem you’ll have with a horrible minmatar standings is that the “antigank” community might spot you traveling in highsec and predict your route. They will then not just bring a few toons to camp a gate they predict you to pass through, but also use a horrible minmatar standings alt to pull the faction army onto that gate, resulting in the faction army already being there when you enter the system, instead of only landing there at a 10 second delay. When you drop your gate cloak and start aligning, the anti-ganker tackles you, and after the 5 second delay, the faction army will start shooting you, too. The tackling antiganker will get CONCORD-ed, but CONCORD will not attack the faction army, so even if you survive until concord lands and wrecks the antiganker, the army will likely wreck you, and the antiganker gets the killmail for it, while his alt(s) steal your loot.