Some will argue that the rudder is better because it'll save you time allowing you to make more journeys per day and I'm not arguing against that RS3 Gold, however I've always performed ports in a more relaxing and less efficient manner and I've always put the it last.
Then port-specific issues: What's the best port to upgrade? I've observed that most upgrades are fairly expensive. I've tried to upgrade my workstation to unlock a third ship but it's incredibly slow to collect bamboo.
In the ideal scenario, you'll want to focus on those upgrades that allow you to unlock new ships for obvious reasons, and you're on the right track. I'm convinced that all upgrades are worth it (except for the instances where there's more than one, in which case you'll be able to unlock them all however you only have one active at the same time therefore, you must choose wisely).
About the crew I basically have four bureaucrats (well it's best to choose the top ones available at the time, but I'm unable to recall the names of any others thus why I selected bureaucrat - which is the one who improves the performance of the other crew members) Crew members; And there are 4 Morale, 5 Seafaring and 4 Combat crew members 3 Merchants; 4 special crew members (the ones who are unlockable through special expeditions such as Feral Chimera)
This crew arrangement has always been successful for me, however there are likely to be better options. I'll probably get rid of Merchants and Merchants shortly and will soon be able to get more special crew members or something since I seldom use Merchants Buy OSRS Gold. I only used them in the process of acquiring trade items to create the armours.