Hi,
Thank you for your query.
I appreciate your interest in the Dynamics 365 products and communty.
Let me answer your questions in the same order you asked:
1 - Integrations:
Dynamics 365 for Sales is built on top of the PowerApps (Dataverse) platform. Using PowerAutmate we can build no-code integrations with external systems (using readily available connectors, APIs, or custom connectors). Also, Dynamics 365 for Sales have built-in ODAT APIs which can be used in any platform for integrations (it supports CRDU and other operations using HTTP methods).
Furthermore, Zapier also has a ready-to-use connector for Dynamics 365 for Sales (CRM) integration:
Connect your Microsoft Office 365 to Microsoft Dynamics 365 CRM integration in 2 minutes | Zapier
2 - Quote Generation
In my opinion, Dynamics 365 Quote process is good enough for general scenarios, for part orders, you might have to customize it a bit (which is not a big deal as customization is mostly No or Low code).
Further evaluation can be performed based on your exact requirements.
More on Quotes:
Create and manage quotes - Sales Professional | Microsoft Docs
3 - Customer Management:
Dynamics 365 for Sales Customer module is quite extensive, you can very easily track collaboration with your customers, do follow-ups, assign tasks to your salesforce team, escalate not contacted customers, track goals (per team or salesperson), reporting, automated notifications, and processes are also available.
Overview of Sales Insights Add-in for Dynamics 365 Sales - Dynamics 365 AI | Microsoft Docs
You can also utilize AI features such as Sales Insights with tools like Relationship Assitant to understand how effective is your collaboration with customers.
Overview of Sales Insights Add-in for Dynamics 365 Sales - Dynamics 365 AI | Microsoft Docs
4 - Automation
You can utilize Processes and Power Automate Flows to automate your organizational and personal flows, not only withing Dynamics but also with Microsoft and non-Microsoft products.
Business process flows overview Dynamics 365 Customer Engagement (on-premises) | Microsoft Docs
Workflow processes with Dynamics 365 for Customer Engagement (on-premises) | Microsoft Docs
Create a cloud flow with Dynamics 365 (online) - Power Automate | Microsoft Docs
I would suggest, to create a Trial (it's free for 30 days) and try it yourself.
Start a Free Trial for Microsoft Dynamics 365| Microsoft Dynamics 365
Also, you can get assisted demos from Microsoft, you can also evaluate the product with a Microsoft partner to get more relevant answers.
Dynamics 365 Partners | Microsoft Dynamics 365
I would like to mention that Dynamics 365 has a strong and vast community, contributors support users/admins/developers to accelerate their projects and make them a success.
There are community tools available (free) to help you with certain tasks (like Ribbon Workbench and XRM Toolbox).
To summarize, Dynamics 365 is packed with features and as a platform, PowerApps/Dataverse is highly customizable (and mostly no/low code), which makes it a perfect choice.