Hello
The verb "preći" can be used with or without "preko." But, since that verb is perfective, it can't be used in present tense, only in future.
So both options:
1. "Preći ću most" / "Ja ću preći most" / "Ja ću da pređem most"
2. "Preći ću preko mosta" / "Ja ću preći preko mosta" / "Ja ću da pređem preko mosta"
...are correct.
However, if you want to use present tense, you have to also use the imperfective aspect of that verb, which is the verb "prelaziti"
1. "(Ja) Prelazim most"
2. "(Ja) Prelazim preko mosta"
(once again, both are correct)
You can hear both options in everyday speech, although the first option may be more frequent, since it's shorter. However, in literary language, the second, longer option is rather used.
Also, once again, all these options:
1. "Naredio si mi da pređem most koji ne mogu preći."
2. "Naredio si mi da pređem preko mosta koji ne mogu preći."
3. "Naredio si mi da pređem most preko kojeg ne mogu preći."
4. "Naredio si mi da pređem preko mosta, preko kojeg ne mogu preći."
...are indeed correct.