@kerplunkSimiliarly to when you should buy new underwear, if you are asking the question, then you probably already have your answer.
Perhaps, but inquiries matter with respect to the rest of your profile. Using your example above, it would matter with respect to the rest of someone's underwear inventory. If they have 15 brand new pairs and are considering replacing 3 shot pairs, that's a lot different than someone with 15 shot pairs and 3 new pairs that's also considering replacements.
If you've got 10 new accounts in the last 2 months, I'd stay away from apps for a solid year to be honest. That way all of your inquiries will become unscoreable and your AoYA will reach 12 months. You'll also cross AAoA of 12 months, which will further help as will 24 months on AoOA as well. When that happens your scores based on where they sit now would be 720-735 easily, without any changes to your utilization. Depending on if you can cross utilization thresholds as well between now and then, there's no reason to believe you couldn't exceed that score range.
That being said, if all of your scores are 720-735+ you'd stand a very good chance at being approved for most credit products if you're talking a clean file with respectable (but not perfect) utilization. Your file will still be relatively young of course, but 2+ years AoOA, > 1 year AAoA and > 1 year AoYA is still a fairly reasonable look and start that most lenders would be comfortable with.
If you've got 10 new accounts in the last 2 months, I'd stay away from apps for a solid year to be honest.
It depends on how that rounding is being done. A displayed "29%" could a true (say) 28.6%, or if the rounding software goes down it could also be a true 29.4%. Just do the math yourself and know that the FICO algorithm rounds any decimal up to the next whole number. If you're at 29.xx%, it is being rounded up to 30% in the eyes of the algorithm and you are above the threshold that you're close to.
As for your secured card, have you contacted CO about unsecuring it? Perhaps that could be done and you could ask for a CLI right after and make the card more workable for you. From that point maybe you could PC it to something worthwhile like a Quicksilver.