Waitress makes much more then cleaner. It'd be hard to find English speaking cleaner in fact. If you are not interested in professional tour guides....I'd say expect to pay 100 PLN a day - you should be able to find someone for that price or contact someone who'd like to do it for free. Maybe through couchsurfing.com if you don't expect "professional" conduct.
You're going to need to spend a lot more than 100 PLN per day. I'd be thinking that it would be at least a few hundred PLN per day and quite possibly 100 PLN per hour.
Just knowing decent English is enough to earn somebody in Warsaw 20 PLN per hour. To know about the city as well will add a lot more.