The grind gets a lot better. Once you get the equipment and skill to run Overkill-level missions, you'll be swimming in cash and XP (coughHoxtonBreakoutcough). When I hit 0-100, I was just sitting on $60M. So, yeah, that won't be a problem.

As for Shadow Raid, yeah, it can be frustrating. However, since you're new to the game, I imagine you don't have the ability to get down to 3 detection yet. Once your skills, perks, and weapons are able to get your detection down, you should have a much better time of it. Doesn't make bad spawns any less frustrating, though, even when running with your main crew.

Missions that are basically impossible w/o high-level talents: Shadow Raid and any long mission in stealth (you need the detection reduction), Big Oil (ECM Overdrive/Shaped Charge), Transport (the Saw). Higher-difficulty loud missions will be impossible without the Combined Tactical Vest.

Essential DLC:

• Big Bank - Not an easy mission by any means, but it is easily one of the best missions in the game. Ode to Greed, its background song, is amazing.
• Hotline Miami - Basically take what I said about Big Bank, except replace "Ode to Greed" with "Evil Eye".
• Gage Weapon Pack #1 - Gives you grenades. You need grenades.
• Gage Mod Courier - You know those little collectable packages hidden in each level? This DLC is the purpose behind them. Collect enough of each type to unlock tons of weapon mods, from scopes to laser sights to barrel attachments.

Note: If you intend to play mainly with your friends, only one of you really needs to grab Big Bank and Hotline Miami, as only the host needs the DLC to get the mission. Anyone can join.