yes it does sound like synchro issue,but the 5 speed is supposed to be a better design of transmission. your synchro's are what help select a gear(it uses friction to enable the gears to engage). if it IS synchro issue,you'd be better putting it into get repaired,but make sure that the specialist preloads them properly or you'll get the same issue all over again. I bought 2 used gearboxes that both had same synchro problem. its always 1st/2nd gear syncs that go 1st cos theyre most used gears etc.
Now if your car has been driven with a slightly dragging clutch,which i DO think is possible due to your clutch pedal issue(master cylinder),then it degrades the said synchros much faster as the clutch cant stop input shaft spinning completely,& gears are hashed instead of synchronising.Hows your reverse gear? sometimes a hard 1st / reverse gear symptom can be a sign of a DMF going,but not always. The only way to tell is by removing gearbox opening it,& stripping it down.(very time consuming & specialist job).
All depends how much time and money you wanna spend. cant remember if your car has the linkage /cables etc. Have you tried adjusting the cable at gearbox end? you might have the box that needs the special tool thing though. worth a try though. there must be a guide somewhere online for doing it. Mines is just a case of putting into 4th gear at box(with the tower),getting someone to hold gearstick agains the stop in 4th position,then unsnap the clip on selector cable,then snap it back into place.and voila