Sounds like the aforementioned E-M5 is worth a look, as is the NEX6. Both would seem to meet on pretty much all needs. Sony NEX peaking is probably about the best out there, with adjustable strength and color to suit needs.
And just to confirm, there's no limit on Bulb mode on Sony NEX or Alpha cameras.
Sony DSLR-A68 / Sony 18-250mm / Minolta 50mm F1.7 / Tamron 150-600mm / Minolta 300mm F4 APO
Sony A6300 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / FE70-200mm F4 G OSS / FE70-300mm F4.5-5.6 G OSS / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses