The fonts usage is subject t its own copyright issues. If you bought the font its fine to use it. If the font is protected private property then it is not. If this font is very similiar to an existing font then copyright is left up to the lawyers
The Beatles artwork is copyrighted.
Do they infringe on the Beatles brand? That is a legal question with no Yes or No answer until the lawyers decide.
I think a general legal approach/strategy is a good idea. "Yes, the font and design were taken from the Beatles brand. We have changed it enough that no one would mistake this for the Beatles own work. It is a tribute to them, we are a tribute to them." If it enters a legal battle than I think the first step would be an order for you to stop using it. That sounds not so bad to me.