Fibre Connections Between Switches - Thoughts?

Hi

I am slightly out of my normal area of working, so need some advice from those in the know...

Currently, I have 4 Linksys SRW2048 Managed Gigabit Switches in my Network, And have just purchased two new DELL Powerconnect 6248 Switches to form part of our Core Infrastructure.

I have two racks of Production Servers, and one Comms Rack + An Additional Non Production Rack

Rack 1 - Production Servers and SAN Backend (Dell Powerconnect 6248 in Rack)
Rack 2 - Production Servers and Routers (Linksys SRW2048 In Rack)
Comms Rack - 3 x Linksys SRW 2048 Switches + 1x Dell PowerConnect 6248

I am thinking i will swap the SRW in the second Rack, and replace it with a Powerconnect Switch. So effectively all servers and systems run across the high end switches, and the patch and additional non production servers link to the SRW's (4) so a rought diagram as follows

6248    ---     6248    ---    SRW2048
                                        SRW2048
                                        SRW2048
                                        SRW2048

Now, In regards to connecting these switches....So far, I have basic Uplinking between switches, using a standard Gigabit Cat5 Cable between switches...There is no management on these things at the moment, basic plug and play...With my logic, i would therefore be having bottlenecks between switches of 1Gb....correct?

I would like to make use of the SFP modules I own for both Dell Switches AND Linksys Switches..What is the best way to go about this? Both Switch Types have 4 SFP Expansion Slots...How should i go about Linking these switches for redundancy and speed?

As a Side note... In an example, 2 Switch config, Uplinked with Fibre, Does this need just one SFP per Switch, or two? If its two, why is it two? I dont understand a lot about Fibre as yet

Thanks