BEEEEEEEEP fuel gauge, speedo, engine temp gauge

Right I got a seat ibiza 1.4 chill 2001 model and ive had the car for a few months and ive recently changed to gearbox (gearbox thought it was fun to hide forth gear from me) job went fine no problems but the day after the speedo stoped working completely and every time I turn a corner brake or speed up even in the most gingerly way the dam fuel warning light keeps beeping at me no matter how full my tank is I watch the needle go up and down all day its driving me insane please help me to fix this problem even if its where the buzzer is located so I can remove it I am completely stumped plus the temp gauge cant make its mind whether to stay on or be off completely and ideas cheers