1. Wiiconnect24 will not ruin your softmod, I have it on all the time. Just don't accept any messages that pop up saying "you need to update your system menu" and you'll be fine. Add friends as you normally would - this is how I have added friends.
2. Try installing the d2x cIOS pack - this is known to make a lot of games work. I'll try to post a link in a few moments.
EDIT: The link to the d2x installation guide is:
And by the way, what system menu are you currently on? A syscheck wouldn't hurt, maybe you should post that up if d2x does not work for you.