Grats on purchase man, welcome to the gang

As for the 24-70, perhaps can ask Yannick or Creativephoto whether they have 2nd hand units to sell?

Welcome to world of FF

Why dont try search garage sales for 24-70?

https://www.facebook.com/irvinfr87/posts/763005330381551

not sure you see this post or not, you might can give it a shot for 2nd hand unit... new one i think still same gua for the price... 5.7-6k?

http://shashinki.com/shop/advanced_search_...1&Submit=Search

for me, lightroom is easy to use but it uses a lot of RAM and PC resources

try photoshop, i find it less resource hogging so maybe can perform better for your case, but i'm bad with photoshop

Nikkor 24-70mm F2.8 probably still around RM5.7k I suppose, prices of lenses seldom fluctuate very much 
Not familiar with Tamron 

tamron 24-70 is around 2.9k i suppose. from dxomark, it has quite good sharpness bt at 70mm a little softer than nikon 2470. even the nikon 2470 is soft at 70mm iirc. that's on paper. in real world, have to ask those who uses them lo. bt i heard 2470 tammy is great value, just like it's tamron 17-50 2.8 on the DX.