1) Sure, it never hurts to ask for a raise. The range would depend on a bunch of factors, such as your location. Try looking up the salary of your position online, such as "technical manager salary" or "engineering manager salary" or something like that.
2) Assuming you will be managing individual contributors (and not managers), there are two basic types of first-line software managers:
2.1) Managers who need to still be individual contributors. These are the types where you will still be expected to do some of the former work you did before. It's a lot like being a technical lead, except you are suddenly now thrust into a world of people management. Most technology companies view first-line managers as having this kind of a responsibility, though larger corporations with more established hierarchies may not.
2.2) Managers who are not expected to be individual contributors anymore. This is a role where your responsibilities are managing the projects and people on your team. (If your company has project managers, then that aspect of the role won't be necessary.) In terms of people management, the responsibilities include managing the career growth of the individual contributors in your team, removing roadblocks from their paths (i.e. political, bureaucratic, etc), potentially moving them around from project to project to better allocate your resources to company priorities, recruit and retain people on your team, mentor and train junior employees, set and reinforce a team culture, and think strategically about how to make your entire team more productive.
3) If your company offers management training, take it. If you like to read, there are a ton of great management books out there. One of my personal favs is "Now, Discover Your Strengths", though you can find plenty of recommendations online if you search around. Talk to managers, senior managers, directors, and VPs that you admire; interview them and ask them how they do their jobs. HR or your manager will likely give you a bunch of information on how to do performance reviews for your team. The art of delivering constructive feedback can totally be learned, though if you are new to it, it may take some time to become comfortable doing it.
This is all just off the top of my head. I'm sure I'm missing a lot of other info, but this ought to be a good start.
Being a manager is not for everyone. Some call it "herding cats," which it may sometimes feel like. But it can also be a tremendously rewarding role, especially when you can set everyone up for success and can see them humming along efficiently and effectively.
Good luck!