Re: Breakfalls can be a problem!
Apparently there are stylistic differences between how you and I take ukemi and our ideas/theories on ukemi are by far polar opposites. I am not about to write a book to explain how I take ukemi or for that fact how anyone else should take ukemi. That instruction is better left to your teacher.
Good ukemi to start is any fall that you can get up from unharmed. It doesnt matter if if it is a forward roll, back fall, high fall, safety is the paramount. However you choose to take your ukemi is good in my book. And Henka waza is changing techniques, Keishi(sp) waza is the reversals sorry about that mixup.
The ikkyo situation, well practice it, and see how and where you can roll out of it. You can roll out of ikkyo when it is first applied and you can roll out of the pin as well. I ll leave it up to you to find where and when. Again differ to your teacher if you cant find how.
As for the last, In brief, I am going to assume you describing direct versions of said techniques meaning the techniques applied to drive uke straight down rather out and away. Put the uncaptured hand on the mat and flare out the feet behind me. Flaring up and out if I have the time and feeling flexiable, or just out, away to spread my body out to spare the shoulder.
Nikyo is received by kneeling with the captured arm, leg being "up" or kneeling, free leg is under the body with live toes. Sometimes I will be forced into having the "up" knee reversed, but for the most its the 1st scenerio. This is done to help shield "some"of the potential atemis. I never had experienced a nikyo where I had to take as you call front break falls. Though I can see the situation where that might happen, my ukemi has never put me in spot where the "front" breakfall was needed. Always from the kneeling position first, then adjusting to where Nage take the the technique next.
Finally I dont condemn anything training wise. I am sure there are merits for just about anything you do. There maybe more efficient ways of going about things, but dont look to me judge right or wrong. I can advise according to what I have been taught, what you take of it is what you take. Sometimes I dont agree with a certain takes on techniques but I dont rule them out. I am sure there is a use for it somewhere. Just like " A break fall is good ukemi gone bad" ,right now you dont see the use for it, maybe in the future you will.
To end my spin on this, Rolling(back or forward) will serve most of your ukemi purposes. Rolling also serves as the basis for advancing to higher levels of ukemi, namely Break/High falls. High falls are not a necessity but an option. If you have any questions concerning how to , when to , why to roll during ukemi consult your dojo seniors or instructors.