No, transferring it over will be just fine. Fermenting does not require the vessel to be completely airtight, it has very little to do with the fermenting process. The reason you keep it airtight is so that you aren't introducing foreign bacteria from the air and other bad things into the beer when its at the most sensitive stage. It also allows the buildup of CO2 which help ensure you are not oxidizing your beer which could lead to off flavors. Sanitization is much more important than an airtight fermentation vessel in my opinion.
As for transferring to secondary, yes, you could transfer to your normal fermenter after 10-14 days and then let it sit there for another week or two. There are many people who do this and you will have perfectly good beer. The most important thing in this part is to ensure you sanitize your fermenter very well and sanitize that racking cake. When you rack to secondary, just make sure you are carefully transferring it over so you do not oxidize the beer.
In fact, when you transfer it over, it may continue to drop in gravity a little bit as you transfer over some yeast in the process. Again, this is completely safe to do as long as everything is sanitized. I keep saying it, but its so important. Otherwise you should be perfectly safe to transfer it over.