can ashkenazi jew kasher glass milk bottle?

To the Questioner, 

1. This question involves a large spectrum of opinions among the Ashkenazic Poskim. 

Therefore, it is best, if at all possible to have two separate bottles, to do so. 

However, if this is not possible, then one who follows the opinion of Rabbi Moshe Weiss z"l would be able to kasher the bottle and use it afterwards for meat. 

One who follows the opinion of Rabbi Shlomo Zalman Aurbach z"l, would be able to do so even without kashering the bottle, just by washing it out thoughroghly once it has been totally cleaning from any sort of remnants. 

2. It is always permitted to say just the verses of Birkat Kohanim that are written in the Torah if you read them directly from the Torah (Bamidbar 6-24).

If you meant in your question whether the actual Kohanim should bless a congregation when there is no minyan - they cannot;

If you meant whether the actual Kohanim should bless a congregation, even when there is a minyan, just you are not praying yet in a Shul - Ashkenazim would not do so outside of Eretz Yisrael, except for Tefillat Mussaf on Yom Tov.

If you meant whether you yourselves can say the bracha of the mitzva that the Kohanim have to bless the congregation, only a male Kohen can.

If you meant whether you can add the words of Birkat Kohanim that are added by the Chazan in the reveiw of the Shmoneh Esrei when there is a minyan - that part may be said and should be said, even if the prayers are not done in a Shul.

If you meant whether you can add the words of Birkat Kohanim that are added by the Chazan in the reveiw of the Shmoneh Esrei when there is less than a minyan, or to add them by yourself within your own Shmoneh Esrei when you are praying yourself, you may not. 

With blessings for a Happy Shavuot, 

Rav Nachum