He doesn't reply every time but I do know he's busy. It's usually things I've forgotten to mention when I see him. He never messages me first so I just feel sometimes I'm bothering him. It doesn't seem to stop him wanting to talk to me in person though.
Probably not. If he stops replying completely I'd give it a break, but that's not the case. Since he likes talking to you you're probably not bothering him when you text :)
That's not a lot in my opinion. But if he doesn't answer back, quit texting him. Some guys just aren't testers (like my boyfriend).