I have not had any of those bugs, even pre-patch. If you haven’t tried the 1.1 patch appropriate for your version (cd/US or digital download), you might want to give that a shot.
Cash: you need to get into the CIA headquarters and possibly the NSA post (I forget exactly which nets you more) in Rome ASAP. The bugs you put in give you Halbech blackmail emails every couple of missions, which you can use against them for 15k (by far the best use of them).
Buy only intel that expands dossiers, provides bonus objectives, or bonus loot. Skip sniper rifles, maps, and if you can handle a little more challenge, worse guards.
Prioritize, and don’t get intermediate armors. For a stealth character, buying nothing but the advanced stealth suit in Moscow is the most frugal path, and just dealing with the civilian attire until then is perfectly doable. After that, IMO, you prioritize the 3 star UC pistol, which will be another chunk of change. Beyond that, I do not buy mods, I find them (eg the Silencer Mark 3 is always in CIA mission. Taipei hotel mission has many other mods. etc).
Sell everything that isn’t equipped, apart from mods that you just can’t fit in because you are in civilian attire still. Grenades and ammo are not really lucrative; golden weapons (from killing certain bosses and minibosses), armors, and mods can be. Sell all the fluff.
Sabotage +50% for hacking can be lucrative, depending on your perspective. I find with a recruit I can reliably get 2 in Sabotage, brilliance level 1 in tech, and maxed pistol and stealth and have to forgo other things like that. Obviously with veteran it’s a nonissue.
I finished a normal game as a recruit just now, with a 380k surplus and tons of equipment. A lot of it is just not missing pickups or hacks, and not bleeding cash through unnecessary intel or gadget purchases, imo.