1. Proficiency bonus:
but would rescale it to +2, +3 at 4th level, +4 at 8th, +5 at 12th, +6 at 16th, +7 at 20th
2. Basic Attack action would be with 2 attacks per Action from 1st level. More attacks give more consistent damage.
"martial" classes would get 1 extra attack per 4 levels,
semi martial would get 1 extra attack per 5 or 6 levels,
non martials, 1 extra attack per 8 levels
that would be easier to track for multiclass.
also 2WF would just add +50% to number of attacks(round up) divided equally between weapons.
I.E. 3 attacks per Action, would turn into 2WF 3 attacks main hand, 2 attacks off hand. with light weapons as normal.
3. scaling at will cantrips, but would follow scaling levels from proficiency increase at levels 4,8,12,16 and 20.
4. having feats and ASIs linked to charcter level with proficiency bonus and not class levels.
Class level can give extra feats that are bonus to standard amount of feats.
5. Every character would get extra skill/tool/language proficiency based on character level and at levels 9,11,13,15,17 and 19 one expertise at those levels.
Expert classes would get their extra from class levels and much sooner, from 1st level onward.
6. Most, if not all "new" features would be gained by 10th level, from that only improvements or additional usages.