Yes.
If this is for a salt water application you have to recognize the corrosion rate of two exposed dissimilar metals is much greater than for a single alloy of the same metal. Essentially, the two exposed alloys become a battery in in the presence of salt water. You experience galvanic corrosion. Even with fresh water there will be galvanic corrosion, but not to the same extent as in salt water.
Al
Yes It welds fine , I never could tell much difference welding 5052 to 5052 or to 6061. The 6061 is good above the waterline but not the best choice below , copper content of the 6061 has a potential to cause electrolysis
Tom