Thunderbird cannot do the reminders and tasks like Outlook.
I use Thunderbird and love it. It is safer than OL or OE. But for what you use it for you need OL.
TB is great for just email. The only thing I use OL for is to get my email from the company Exchange server. I wish they would make TB compatible with things like that. I really hate using OL or OE.
Firefox on the other hand can be used and will help tremendously with security.
Ultimate Edition Linux
AMD FX 8350
Asus Sabertooth 990FX R2.0
24GB GSkill/Corsair 1866MHz
EVGA GTX 970 SSC/ GTX 650 (PhysX)
SSD - OCZ V4 128GB/Kingston 120GB
HDD - 3TB/2x 750GB/500GB
CM HAF 932 Red
CM Hyper 212 EVO w/2x 120mm Red
Logitech X540 5.1
2X Acer 23" LED - Surround: 3840x1080
Microsoft Sidewinder x4 KB
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
- Albert Einstein