That depends on where you are coming from. English has enough German and Latin roots that most of Europe has a head start when learning English. (linguists will define roots different from what I’m using and say English doesn’t have Latin roots, but there is still significant influence)
If you are coming from an African language though it probably won’t make much difference. Though in Africa there is a good chance your nation was controlled by Europe over the years and so you might know enough of some European language to make English easier.
That depends on how they act. China right now is on a path where I’d oppose them replacing the US. However the EU has the ability to replace the US as the global superpower - they don’t because despite some significant differences overall the US and EU get along well and so they don’t see any point. By cooperating the EU gains the things they want from being a global superpower without the disadvantages. Part of that cooperation is the EU is in NATO (mostly?) and so they are paying some of the military costs of the US being a global super power.
The US isn’t perfect by any means, but we have done much better in many ways vs previous global superpowers. Right now I’d predict China would be worse so I oppose it. However who knows how things will change in the future.