Mishneh Torah Hilchot Tefilla 15:10 (:9 according to some): נְשִׂיאַת כַּפַּיִם בַּעֲשָׂרָה, וְכוֹהֲנִים מִן הַמִּנְיָן. בֵּית הַכְּנֶסֶת שֶׁכֻּלּוֹ כּוֹהֲנִים, כֻּלָּן נוֹשְׂאִין אֶת כַּפֵּיהֶן; ...
Shulchan Oruch Mishnah Berurah 128 (8)  implies that the Kohanim should go up to bless the people after the prayer leader has said "Retzei". I see that many knowledgeable Kohanim start going up ...
Asking the question because if there is a Jewish person living in the same building that dies in the building, couldn't this pose a problem for a Kohen being under the same roof?
I recently saw some drawings of the Kohen's hands during duchaning, not the way I do it. I put my two first fingers together without leaving a window. I would like to know if there is any valid way ...