Hello, I'm a voip specialist with over 10years of experience working on the TS department of a US voip company; I can install, troubleshoot and customize many SIP devices including: softphones, ATAs, IP-phones and PBX systems like Asterisk/FPBX. I read your project description and I have deployed many SIP installations, I never really used Bicom but I'm quite well experienced with pure Asterisk so it shouldn't be a problem, as far as the Yealink phones, I have setup many Yealinks, Grandstreams, Linksys/Cisco and other voip-phone brands, I'm not a Yealink expert and I never used the Yealink management tool (at least that I recall), but from reading the documentation that is just a portal to auto-provision and get statistic reports from your phones, it should be straight forward to configure and use it. I'm available through chat for further talk.
Thank you.