If you want to look at potential sentence for each count, he sits at a score off about 20 to 26 on the offender score in the US federal sentencing guidelines.
Note, this calculation lacks any criminal history score so I'll speculate it's a 0-1 range but could potentially be 1-3 depending on his prior rap sheet. Felonies ramp this score up the most.
Note, there are no mandatory minimums for these counts, so a judge has sway in their own judgement in sentencing below the guidelines score.
Just taking one count involving the threat on the college because it has the least chances to cop any enhancements;
18 us 844(e)
2.A.6 Base offender level is 12
2332a enhancement applies section 2.M.6.1
The offence involved threats involving a wmd but no means of pulling it off so applies section 2 M6.1, A, section 4, B.
Base offender score plus 8
Count 1: 18 U.S.C. § 2332a
2A6.1(a)(1)Base Offense Level12
§ 2M6.1(a)(4)(B)Base Offense Level+8
§ 2M6.1Higher offense level
Total offense level for this count: 20
This offence level is inside zone D on the guidelines table. He would be unable for placement in halfway home or other suspended release.
Pleading guilty and accepting the crime will drop your score 2 points and if the FBI says you helped and co operative that can sway them to ask for a motion to drop one point.
So maybe 2 points off, 3 if he's lucky.
With admitting guilt he gets a 18 offender score totalling up to guideline sentence range of 27-33 months and a fine.
I am personally interested in the threat against the special agent charge 875(c), he might cop that one and one other count if they press it or indeed press all counts.
This is the pretrial stage, if he can arrange an agreement with a lawyer and the feds and bring forward a plea agreement, his counts may be less or they choose to pick the least problematic one that skates you out from a felony to maybe a misdemeanor.