Worn synchro perhaps. A garage job. If there's a lip on your disc, change them right away. Might want to check your pads too, a new set of discs and pads should sort you out - could be a nice distance between the worn discs and pads which isn't helping you stop any sooner. Vibrating steering wheel most likely means unbalanced wheels (which yours are bound to be, let's face it Chris ) so a new set or having your current ones balanced should sort it. As for heavy and sometimes light - is there ever a squealing noise from under the hood, perhaps when you start it up? If so you could need a belt replacing, which when it slips can cause heavy steering. Check your brake fluid.