Linear/Non-Linear and Fast Travel

[michalius]

A bit of a newbie question here, but I tried multiple searches and nothing came up.

I'm currently a level 7, having just arrived at Freedom Islands after the main quest brought me there. What I'm not sure about is whether or not the game is somewhat linear in that if I traveled to Ellinia, would I be facing armies much more powerful than mine. If it is somewhat manageable, and I am able to travel to other areas at my low level in order to recruit troops, where are the "trains, dirgibles, and submarines" that can take me between continents?

Thanks for the help, and sorry if this has been answered already.