While I am not inherently opposed to some kind of licensing and training scheme, the risks and possible abuses of such a system are too large to ignore.
The only way such a system would work is if the training was provided for free, licenses were provided for free on demand (once background and training requirements were met), and there was no disparate impact. Otherwise, you're talking about restricting the constitutional rights of those who can't afford to pay the fees (poll tax, anyone?).
I cannot support any requirement to show "need." In every case where a "need" has been required, the judgement of what constitutes a valid "need" has always grown more and more stringent until it becomes a de facto ban. See the eventual banning of civilian ownership of firearms in the UK for an example. Another can be found in California's concealed carry permit scheme, in which the county sheriffs have discretion on what constitutes "need" (and usually only approve applications from political doners).
I also do not support any licensing that ties a gun owner to their address and what weapons they own. This amounts to de facto registration, which has always ended in confiscation. The license could, however, be used like a passport. No address, no list of weapons, only the qualification that one is cleared and checked. If you are found to be in possession of firearms and do not have the required license, then you are in the wrong. That is as far as I will support.